An explanation of the SQL TOP clause

SQL top plays an important role in the advanced operations of the database, which is explained in this article.

TOP clause

The TOP clause is used to specify the number of records to return.

The TOP clause is useful for large tables with thousands of records.

Note: Not all database systems support the TOP clause.

Syntax for SQL Server:

SELECT TOP number|percent column_name (s)
From table_name

The SQL SELECT TOP in MySQL and Oracle is equivalent

MySQL syntax

SELECT column_name (s) from Table_namelimit number

Example

SELECT *from Personslimit 5

Oracle syntax

SELECT column_name (s) from Table_namewhere ROWNUM <= number

Example

SELECT *from personswhere ROWNUM <= 5

SQL TOP Instance

Now, we want to select the first two records from the "Persons" table above.

We can use the following SELECT statement:

SELECT TOP 2 * from Persons

This article on the SQL TOP clause to make a related explanation, more learning materials clear focus on the PHP Chinese network can be viewed.