SQL has several ways to limit the number of rows
returned in
a query,
depending on
the database management system being used. Some
of the most common ways to limit the number of rows returned include using
the TOP, LIMIT, FETCH
FIRST, or
ROWNUM clause.
TOP (Microsoft SQL Server): The TOP clause is used to limit the number of rows returned by a query in Microsoft SQL Server. The basic syntax is as follows:
SELECT TOP n column1, column2, ...
FROM table_name
WHERE condition;
Here, n is the maximum number of rows to return. If the TOP clause is not used, all rows that meet the WHERE condition will be returned.
LIMIT (MySQL, PostgreSQL, SQLite): The LIMIT clause is used to limit the number of rows returned by a query in MySQL, PostgreSQL, and SQLite. The basic syntax is as follows:
SELECT column1, column2, ...
FROM table_name
WHERE condition
LIMIT
n;
Here, n is the maximum number of rows to return. If the LIMIT clause is not used, all rows that meet the WHERE condition will be returned.
FETCH FIRST (IBM DB2, Oracle): The FETCH FIRST clause is used to limit the number of rows returned by a query in IBM DB2 and Oracle. The basic syntax is as follows:
SELECT column1, column2, ...
FROM table_name
WHERE condition
FETCH FIRST
n ROWS ONLY;
Here, n is the maximum number of rows to return. If the FETCH FIRST clause is not used, all rows that meet the WHERE condition will be returned.
ROWNUM (Oracle): The ROWNUM pseudo-column is used to limit the number of rows returned by a query in Oracle. The basic syntax is as follows:
SELECT column1, column2, ...
FROM
(
SELECT column1, column2, ...
FROM table_name
WHERE condition
ORDER BY
column1
)
WHERE ROWNUM <= n;
Here, n is the maximum number of rows to return. The subquery is used to apply the WHERE and ORDER BY conditions, and then the outer query uses the ROWNUM pseudo-column to limit the number of rows returned.
I is important to note that the specific syntax and usage of these clauses may vary depending on the database management system being used.
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