Who cannot be used with where in sql

The WHERE clause cannot be used with the following clause: ORDER BY because it must come after the WHERE clause. GROUP BY because it must be placed after the WHERE clause. HAVING because it must be placed after the GROUP BY clause.

What clauses cannot be used with the Where clause?

In SQL, the WHERE clause is used to filter data according to specified conditions. It cannot be used with the following clauses:

1. ORDER BY

The ORDER BY clause is used to sort query results, and it must be placed after the WHERE clause. If you place the ORDER BY clause before the WHERE clause, a syntax error occurs.

-- 语法错误
SELECT * FROM table WHERE condition ORDER BY column_name;

-- 正确用法
SELECT * FROM table WHERE condition ORDER BY column_name;

2. GROUP BY

The GROUP BY clause is used to group data and perform aggregation operations on each group of data. It must be placed after the WHERE clause . A syntax error will also occur if the GROUP BY clause is placed before the WHERE clause.

-- 语法错误
SELECT * FROM table WHERE condition GROUP BY column_name;

-- 正确用法
SELECT * FROM table WHERE condition GROUP BY column_name;

3. HAVING

The HAVING clause is used to filter aggregate results, and it must be placed after the GROUP BY clause. A syntax error will also occur if the HAVING clause is placed before the WHERE clause or the GROUP BY clause.

-- 语法错误
SELECT * FROM table WHERE condition HAVING count(*) > 1;

-- 正确用法
SELECT * FROM table WHERE condition GROUP BY column_name HAVING count(*) > 1;

In short, the WHERE clause can only be used with the SELECT clause and cannot be used with the ORDER BY, GROUP BY and HAVING clauses. The correct order is:

<code>SELECT ...
WHERE ...
GROUP BY ...
HAVING ...
ORDER BY ...</code>

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