Difference between revisions of "SELECT Reference"
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*The WHERE clause determines which rows to show | *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]]. | *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. | *[[SELECT statements may nested|SELECT within SELECT Tutorial]] - 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]] | *The output from a SELECT may be added to another table using [[INSERT .. SELECT]] | ||
*The select statement may aggregate values using a [[GROUP BY]] clause | *The select statement may aggregate values using a [[SELECT .. GROUP BY]] clause | ||
Revision as of 13:31, 27 February 2015
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 within SELECT Tutorial - 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
- The select statement may aggregate values using a SELECT .. GROUP BY clause