SQL TOP clause, SQL LIKE operator, SQL wildcard

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

SQL SELECT TOP in MySQL and Oracle is the 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

The original table (used in the example):

Persons table:

City

Id	LastName	FirstName	Address
1	Adams	John	Oxford Street	London
2	Bush	George	Fifth Avenue	New York
3	Carter	Thomas	Changan Street	Beijing
4	Obama	Barack	Pennsylvania Avenue	Washington

SQL TOP Instance

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

We can use the following SELECT statement:

TOP 2* FROM Persons

Results: City

Id	LastName	FirstName	Address
1	Adams	John	Oxford Street	London
2	Bush	George	Fifth Avenue	New York

SQL TOP PERCENT Instances

Now, we want to select 50% of the records from the "Persons" table above.

We can use the following SELECT statement:

TOP 50 PERCENT* FROM Persons

Results:

City

Id	LastName	FirstName	Address
1	Adams	John	Oxford Street	London
2	Bush	George	Fifth Avenue	New York

SQL TOP clause, SQL LIKE operator, SQL wildcard