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SQL SELECT statement

巴扎黑
巴扎黑Original
2016-11-30 09:50:031047browse

This chapter explains the SELECT and SELECT * statements.

SQL SELECT statement

SELECT statement is used to select data from a table.

The results are stored in a results table (called a result set).

SQL SELECT syntax

SELECT column name FROM table name

and:

SELECT * FROM table name

Note: SQL statements are not case-sensitive. SELECT is equivalent to select.

SQL SELECT Example

To get the contents of the columns named "LastName" and "FirstName" (from the database table named "Persons"), use a SELECT statement like this:

SELECT LastName,FirstName FROM Persons

"Persons" table:

Id LastName FirstName Address City

1 Adams John Oxford Street London Bush George Fifth Avenue New York

3 Carter Thomas Changan Street Beijing

Result:

LastName FirstName

Adams John

Bush George

Carter Thomas

SQL SELECT * Example

Now we want to select all columns from the "Persons" table.

Please use the symbol * instead of column names, like this:

SELECT * FROM Persons


Tip: The asterisk (*) is a shortcut to select all columns.

Results:

Id LastName FirstName Address City

1 Adams John Oxford Street London

2 Bush George Fifth Avenue New York

3 Carter Thomas Changan Street Beijing

Navigate in the result-set (result-set)

The results obtained by the SQL query program are stored in a result set. Most database software systems allow the use of programmatic functions to navigate through result sets, such as: Move-To-First-Record, Get-Record-Content, Move-To-Next-Record, and so on.

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