Hello, !
SELECT
SELECT
is used to determine which fields will be retrieved from the database.
Common Uses
SELECT *
will select all available columns across all tables in your query, including joined tables
SELECT table.*
will select all available columns on the specified table. This is useful when you're joining to another table for filtering, but only want to see the columns on one table.
SELECT table.column
will select only a single field from a single table. You can leave out the table name if you're only querying a single table.
Examples
SELECT * FROM tablename; -- select everything
SELECT field FROM tablename; -- select a single field
SELECT field1, field2 FROM tablename; -- select a multiple fields
SELECT COUNT(*) FROM tablename; -- select the number of rows in a table
AS
AS
is used to create an alias. When used with SELECT
, it is used to create an alias for a field. When used alongside FROM
, AS
will create an alias for a table name.