Difference between revisions of "SELECT Reference"
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The [[SELECT]] command is used to show data from a database. | The [[SELECT]] command is used to show data from a database. | ||
Revision as of 10:51, 13 May 2014
Template:S The SELECT command is used to show data from a database.
The output from a SELECT statement is always a grid - with a number of rows and a number of columns.
Simple SELECT
The simplest SELECT commands involve a single table:
| SQL | Result | ||||||||
|---|---|---|---|---|---|---|---|---|---|
SELECT name, population
FROM bbc
WHERE region='North America'
|
|
- The SELECT line determines which columns to show - in this case
nameandpopulation, both of which are columns of the bbc table. - The WHERE clause determines which rows to show
- The SELECT statement may involve data from more than one table using a JOIN or a UNION.
- SELECT statements may nested - that is the output from one SELECT may be the input to another SELECT.
- The output from a SELECT may be added to another table using INSERT .. SELECT