The syntax of the FROM clause is as follows:
The FROM clause is used in three of the four fundamental SQL commands for data manipulation:
- The FROM clause specifies other table or view sources to be utilized in the search condition of the WHERE clause of a DELETE command, i.e. no rows are deleted from
- The FROM clause specifies other table or view sources from which rows are pulled to make the results of a SELECT command.
- The FROM clause specifies other table or view sources to be utilized in the search condition of the WHERE clause of a UPDATE command, i.e. no rows are updated from
TableSources is a comma-separated list of tables, names and JOIN clauses used by command in which the FROM clause exists.
The table-like items in
TableSources can be aliased with the AS keyword. Once aliased, the table-like items can only be referred to with the alias. This applies especially when using the table to qualify columns. The syntax is as follows:
FROM table [AS] TableAlias [, ...]
The most common FROM clause usage is to specify a single table.
SELECT * FROM tblA
FROM with JOIN
This FROM clause specifies 2 tables joined together to act as one.
DELETE tblA FROM tblA INNER JOIN tblB ON tblB.Name = tblA.Name WHERE tblA.Name = 'George'
FROM with sub-query
This FROM clause specifies a table derived from a sub-query.
SELECT ST.stor_id, ST.stor_name FROM stores AS ST INNER JOIN ( SELECT stor_id, COUNT(DISTINCT title_id) AS title_count FROM sales GROUP BY stor_id ) AS SA ON ST.stor_id = SA.stor_id WHERE SA.title_count = (SELECT COUNT(*) FROM titles)