Difference between revisions of "SELECT Reference"
From SQLZOO
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==Simple SELECT== | ==Simple SELECT== | ||
The simplest SELECT commands involve a single table: | The simplest SELECT commands involve a single table: | ||
| − | <table><tr><td> | + | <table> |
| + | <tr><th>SQL</th><th>Result</th></tr> | ||
| + | <tr><td> | ||
<source lang='sql'> | <source lang='sql'> | ||
SELECT name, population | SELECT name, population | ||
Revision as of 10:15, 11 August 2012
SELECT Operations
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 ta le. - 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
