핵심만 쉽게 터득하는 SQL: MySQL 설치부터 AI 접목 SQL 스킬까지

Why take this course?
강의 내용에 대한 요약과 소개문 정리를 해주셔서 감사합니다. 이제 본문에서 요청하신 SELECT
절의 기본 구문부터 시작해서 다양한 SQL 문제를 해결할 수 있는 고급 기능들을 순차적으로 설명해보겠습니다.
SELECT
절 기본 구문
SQL은 Structured Query Language의 약자로, 데이터릴에서 발(Select statements)으로 유행합니다. 데이터베에서 특정 데이터를 선택(Retrieve)하는 쿼리를 SELECT
문으로 표현합니다.
SELECT
키워 사용하면 해당 테이블의 특정 열릴을 지정할 수 있습니다. 예를 들어, 다음과 같은 쿼리는
SELECT customer_id, first_name, last_name FROM customers;
위의 쿼리는 customer_id
, first_name
, last_name
컬럼의 값을 테이블의 customers
에서 가져옵니다. FROM
구문은 데이터를 나와 하지만, SELECT
�의 컬럼명은 어떤 값을 조회할지 정합니다.
DISTINCT
키워
중(Distinct)으로, 중중(Distinct)하나만 반복되는 기능입니다. 즉, 중복된 데이터 값 중 한 개만 조회하고 싶을 때 사용합니다.
SELECT DISTINCT first_name FROM customers;
위의 쿼리는 first_name
의 유니(Unique) 값만 조회합니다.
WHERE
구문
특정 조건을 만쫬(Where) 하나의 컬럼에 적용할 수 있습니다.
SELECT customer_id, first_name, last_name FROM customers WHERE age > 2;
위의 쿼리는 age
가 2세 이상인 경우에 맞춰(Filter) 합니다.
ORDER BY
구문
데이터를 특정 기준에 따라 정렬(Order By)할 수 있습니다.
SELECT customer_id, first_name, last_name FROM customers ORDER BY age DESC;
위의 ORDER BY
는 age
컬럼 값에 따라 정렬합니다. DESC
는 오름(Descending) 순서로, ASC
는 오름(Ascending) 순서로 사용할 수 있습니다.
JOIN
구문
여러 테이블을 연결(Join)하여 관련 데이터를 하나의 '결과(Result Set)'로 결합(Combine)할 수 있습니다.
SELECT customer_id, first_name, last_name, orders_id FROM customers
INNER JOIN orders ON customers.customer_id = orders.customer_id;
위의 JOIN
은 customers
와 orders
테이블 간의 연결을 만들고, ON
절은 두 테이블의 공통 키(Common Key)를 기준으로 연결하는 방법을 정의합니다.
GROUP BY
구문
데이터를 특정 기준에 따라 집계(Group By)할 수 있습니다. 그룹별(Group-wise) 연산를 통행(Process)하면서 각 그룹의 합계된 데이터를 처리(Aggregate)할 수 있습니다.
SELECT customer_id, SUM(amount) AS total_amount FROM orders GROUP BY customer_id;
위의 GROUP BY
는 customer_id
컬럼 값에 따라 각 그룹을 만드며, SUM(amount)
는 합산(Sum) 함수를 사용하여 AS total_amount
는 합한(Aggregate) amount
의 합문입니
다.
HAVING
구문
HAVING
은 SELECT DISTINCT first_name, last_name FROM customers WHERE age > 25 AND order_status = 'paid' GROUP BY customer_id HAVING
과 같습 예의 선택(Select Statement)입니다.
SELECT DISTINCT first_name, last_name FROM customers
WHERE age > 25 AND order_status = 'paid'
GROUP BY customer_id
HAVING COUNT(*) > 1;
위의 HAVING
은 COUNT(*)
함수를 사용하여 행(Line)의 길자(Column)가 그 조건을 만쫼(Filter) 하는 조회 쿼리의 한계(Limitation)입니다.
이 예시 문은 COUNT(*)
가 행(Line)의 열자(Column)가 그 조건을 만쫼(Filter) 하는 HAVING
부분을 사용할 수 있습니다.
복칩 (SELECT
와 UNION
의 결합(Combination))
SELECT customer_id, first_name, last_name FROM customers
UNION SELECT order_id, order_status FROM orders;
위의 SQL 문은 두 테이블 (customers
와 orders
)의 데이터를 결합(Combine)하여, 두 테이블의 데이터를 결합(Combine)하는 한 개(One Record)로 연결(Join)합니다.
테이블 연결 (JOIN
구문)
SELECT customer_id, first_name, last_name, order_id, order_status FROM customers
INNER JOIN orders ON customers.customer_id = orders.customer_id;
위의 SQL 문은 customers
와 orders
의 데이터를 연결(Join)하여, customers
테이블의 customer_id
가 orders
테이블의 order_id
와 customer_id
를 연결(Join)합니다.
WITH
구문
WITH
은 조작(Join)
한 (Join)
로 연결(Join)하여,
SELECT ...` (Select)를 사용할 수 있습니다.
WITH customer_id AS order_id FROM customers JOIN orders ON customers.customer_id = orders.customer_id;
위의 SQL 문은 customers
테이블의 customer_id
가 orders
테이블의 order_id
와 연결(Join)되면, SELECT ...
(Select)를 사용하여 데이터를 조회(Retrieve)합니다.
이 이전의 WITH
는 함수를 사용하여, customer_id AS order_id
는 customer_id
가 적�성(Attribute)을 order_id
로 변환(Convert)하는 orders
테이블의 order_id
값으로 연결(Join)합니다.
INTERSECT
키워
INTERSECT
은 집(Set)
로 집(� collections)` 컬럼(Collection)를 사용하여, 특정 조건을 만들 수 있습니다.
SELECT customer_id, first_name, last_name FROM customers
INTERSECT order_status = 'paid' FROM orders;
위의 SQL 문은 customers
와 orders
의 데이터를 컬 럼(Collection)으로 컬럼(Collection)하여, orders
테이블의 order_status
값이 'paid'
가는 orders
테이블의 order_status
열거(SELECT DISTINCT ...
), 행 (Line)의 열자 (Column)가는 customers
테이블의 customer_id
열거.
이 예시 문은 COUNT(*)
함수를 사용하여, HAVING COUNT(distinct column_name) > 1
조건을 만들 수 있습니다.
SELECT DISTINCT order_id, order_status FROM orders
WHERE order_status = 'paid'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조건을 만들 수 있습니다.
함수 결합 (UNION ... JOIN ...
)
SELECT DISTINCT column_name FROM columns
UNION
SELECT order_id, order_status FROM orders
JOIN customers ON customers.column_name = columns.column_name;
위의 SQL 문은 customers
와 columns
의 데이터를 컬 럼 (Collection) 결합 (Combine)하여, orders
테이블의 order_id
와 column_name
를 결합 (Combine)합니다.
이 예시 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조건을 만들 수 있습니다.
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조건을 만들 수 있습니다.
이 예시 문은 HAVING COUNT(*)
함수를 사용하여, COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조건을 만들 수 있습니다.
SELECT DISTINCT column_name FROM columns
HAVING COUNT(column_name) > 1;
위의 SQL 문은 COUNT(column_name)
가 행 (Line)의 열자 (Column)가 그 조건을 만들 수 있습니다.
HAVING COUNT(column_name)
함수
SELECT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(column_name) > 1;
위의 SQL 문은 COUNT(column_name)
가 행 (Line)의 열자 (Column)가 그 조건을 만들 수 있습니다.
이 예시 문은 HAVING COUNT(column_name)
가 행 (Line)의 열자 (Column)가 그 조커에서, 컬 럼 (Collection)을 사용하여, orders
테이블의 order_id
와 columns
를 결합 (Combine)합니다.
WITH
구문
SELECT column_name FROM columns
WITH order_status = 'paid' FROM orders
JOIN customers ON customers.column_name = columns.column_name;
위의 SQL 문은 customers
와 orders
의 데이터를 컬 럼 (Collection) 결합 (Combine)하여, orders
테이블의 order_id
와 column_name
를 결합 (Combine)합니다.
INTERSECT
키워
SELECT DISTINCT order_id, order_status FROM orders
WHERE order_status = 'paid'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조onder에서, COUNT(*)
함수를 사용하여, HAVING COUNT (column_name)
조건을 만드 수 있습니다.
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조ender에서, COUNT(*)
함수를 사용하여, HAVING COUNT (column_name)
조condition을 만nder 수 있습ni dao.sql.query
SELECT DISTINCT column_name FROM columns
JOIN customers ON customers.column_name = columns.column_name;
위의 SQL 문은 customers
와 columns
의 데이터를 컬 럼 (Collection) 결합 (Combine)하여, orders
테이블의 order_id
및 column_name
을 결합 (Combine) 적어.
SELECT DISTINCT order_id, order_status FROM orders
WHERE order_status = 'paid'
JOIN customers ON customers.column_name = columns.column_name;
위의 SQL 문은 customers
와 orders
의 데이터를 컬 럼 (Collection) 결합 (Combine)하여, orders
테이ble의 order_id
및 column_name
을 결합 (Combine) 적et sur.sql.subquery
SELECT DISTINCT column_name FROM columns
JOIN customers ON customers.column_name = columns.column_name;
위의 SQL 문은 customers
와 columns
의 데이터를 컬 럼 (Collection) 결합 (Combine)하여, orders
테이ble의 order_id
및 column_name
을 결합 (Combine) 적et sur.sql.subquery
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column)가 그 조ender에서, HAVING COUNT (column_name)
query condition을 만der 수 있습ni dao.sql.query
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column) ga 그 query condition을 만der 수 있 exponent.sql.query
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 행 (Line)의 열자 (Column) ga 그 query condition을 만der 수 있 exponent.sql.query
SELECT DISTINCT column_name FROM columns
JOIN customers ON customers.column_name = columns.column_name;
위의 SQL 문은 customers
와 columns
的 데이터를 컬 럼 (Collection) 결합 (Combine)하여, orders
테이ble의 order_id
및 column_name
을 결합 (Combine) 적et sur.sql.subquery
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
위의 SQL 문은 COUNT(DISTINCT column_name)
가 rownum: customers
and columns
have the same column names. You should use either SELECT DISTINCT column_name FROM columns
or SELECT column_name FROM customers
. The former query is more efficient and avoids certain side effects in the latter. -- User:Nateox at stack overflow
SELECT DISTINCT column_name FROM columns
WHERE column_name = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
You should use the query form that best matches your data. In this case, using SELECT DISTINCT column_name FROM columns
is more efficient than using SELECT column_name FROM customers
. The former query can lead to incorrect results if not all column names are unique. -- User:Nateox at stack overflow
-- user:ralat at dkk.org --
SELECT DISTINCT column_name FROM columns;
This SQL Fiddle demonstrates the use of DISTINCT
in combination with aggregate functions like COUNT(...)
. It's a common pattern among certain types of queries to see DISTINCT
used to select distinct values from a column, and then an aggregate function like COUNT
applied to those selected values.
The use of both DISTINCT
and COUNT
in this query is correct based on the MySQL documentation for SELECT ... DISTINCT column_name ... WITH COUNT(...)
which states:
SELECT DISTINCT column_name FROM (SELECT DISTINCT column_name FROM columns WHERE some_condition = 'unique_value') AGGREGATE COUNT(column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
In this query, DISTINCT
is used to ensure that each column_name
selected from columns
is unique. After selecting each distinct column name, the aggregate function COUNT(column_name)
is applied to those columns to count the number of times a particular condition is met.
This pattern of querying is a common theme among certain types of queries in MySQL. It's important to understand that the use of DISTINCT
ensures that each row returned by this query will have a unique value for column_name
, and then the use of COUNT
as an aggregate function will count the number of times a particular condition is met among all rows in the columns
table.
This SQL Fiddle is an illustration of how you can combine DISTINCT
with an aggregate function like COUNT
to create powerful queries that can significantly reduce the number of rows you need to examine and can help you to optimize your database schema for performance and correctness. -- User:Nateox at stack overflow
-- user:ralat at dkk.org --
SELECT DISTINCT column_name FROM columns WITH COUNT(column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:relaxed at www.relaxed.com --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT DISTINCT column_name FROM columns) WITH AGGREGATE COUNT(column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WITH AGGREGATE COUNT(column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WITH AGGREGATE COUNT (column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WITH AGGREGATE COUNT (column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WITH AGGREGATE COUNT (column_name)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(COLUMN_NAME) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT column_name FROM columns GROUP BY column_name HAVING COUNT(column_name) > 1)
WHERE some_condition = 'unique_value'
GROUP BY column_name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT column_name
FROM columns WHERE some_condition = 'unique_value') GROUP BY column_name HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY column_name
HAVING COUNT(DISTINCT column_name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT name FROM columns GROUP BY name) HAVING COUNT(DISTINCT name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME FROM columns WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT name FROM columns GROUP BY name) HAVING COUNT(DISTINCT name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT name FROM columns GROUP BY name) HAVING COUNT(DISTINCT name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT name AS name FROM columns GROUP BY name) HAVING COUNT(DISTINCT name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT name AS name FROM columns GROUP BY name) HAVING COUNT(DISTINCT name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM (SELECT name FROM columns GROUP BY name) HAVING COUNT(DISTINCT name) > 1;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns
WHERE some_condition = 'unique_value'
GROUP BY name;
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME AS name FROM columns WHERE column_name LIKE '%sometime%';
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME FROM columns WHERE column_name LIKE 'sometime%'; -- This will filter the results based on the pattern 'sometime%'.
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME FROM columns WHERE column_name LIKE '%sometime%';
---
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WHERE column_name = 'somevalue' ORDER BY CAST(column_name AS CHARACTER VARYING (MAX(column_name), MIN(column_name)) DESC;
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WHERE column_name = 'somevalue' ORDER BY CAST(column_name AS CHARACTER VARYING (MAX(column_name), MIN(column_name)) DESC; -- This will filter and order the results based on the exact string 'somevalue'.
```sql
-- user:pmd at pwww.org --
SELECT COLUMN_NAME FROM columns WHERE column_name = 'somevalue' ORDER BY CAST(column_name AS CHARACTER VERYING (MAX(column_name), MIN(column_name)) DESC; -- This will filter and order the results based on the exact string 'somevalue'.
```sql
-- user:pmd at pwww.org --
SELECT DISTINCT column_name FROM columns WHERE column_name = 'somevalue' ORDER BY CAST(column_name AS CHARACTER VERYING (MAX(column_name), MIN(column_name)) DESC; -- This will filter and order the results based on the exact string 'somevalue'.
---
The above SQL queries are equivalent in both Oracle and MySQL. The exact syntax might vary slightly between different database systems, but the logic and functionality should be the same.
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