306viewsSQL FOREIGN KEY constraint represents relationship between tables. A Foreign Key is a column(s) whose values are derived from the PRIMARY KEY or UNIQUE KEY of some other table. If you want to associate records of...
by Manzoor Siddiqui · Published September 21, 2015 · Last modified September 28, 2015
333viewsSQL PRIMARY KEY constraint uniquely identifies each row in a database table. A primary key column cannot have NULL values. A table can have only one primary key with single or multiple fields. Primary...
by Manzoor Siddiqui · Published September 20, 2015 · Last modified September 26, 2015
355views SQL UNION ALL operator is used to combine the results of two or more SELECT statements. Each SELECT statement within the UNION ALL must have the same number of columns and all columns should...
by Manzoor Siddiqui · Published September 19, 2015 · Last modified October 6, 2015
453views SQL UNION operator is used to combine the results of two or more SELECT statements. Each SELECT statement within the UNION must have the same number of columns and all columns should have same...
SQL Commands / SQL Programming / SQL Server
by Manzoor Siddiqui · Published September 18, 2015 · Last modified September 23, 2015
754viewsSQL CROSS JOIN returns all records where each row from the first table is combined with each row of the second table. CROSS JOIN returns the Cartesian product of the tables involved in join if...
SQL Commands / SQL Programming / SQL Server
by Manzoor Siddiqui · Published September 17, 2015 · Last modified September 23, 2015
SQL FULL JOIN returns all the rows from the left table and all the rows from the right table. If there are no matching values in either of the tables then non-matching values returned as NULL....
