In this tutorial, you have learned how to use the MySQL DELETE JOIN statement to delete data from two or more tables. The query returned an empty result set which is what we expected. Orders o ON c.customerNumber = o.customerNumber We can verify the delete by finding whether customers who do not have any order exists using the following query: SELECT OrderNumber IS NULL Code language: SQL (Structured Query Language) ( sql ) Orders ON customers.customerNumber = orders.customerNumber The following statement removes customers who have not placed any order: DELETE customers We can use DELETE statement with LEFT JOIN clause to clean up our customers master data. However, each order belongs to one and only one customer. See the following customers and orders tables in the sample database:Įach customer has zero or more orders. Note that we only put T1 table after the DELETE keyword, not both T1 and T2 tables like we did with the INNER JOIN clause. T2.key IS NULL Code language: SQL (Structured Query Language) ( sql ) The following syntax illustrates how to use DELETE statement with LEFT JOIN clause to delete rows from T1 table that does not have corresponding rows in the T2 table: DELETE T1 We can also use the LEFT JOIN clause in the DELETE statement to delete rows in a table (left table) that does not have matching rows in another table (right table). We often use the LEFT JOIN clause in the SELECT statement to find rows in the left table that have or don’t have matching rows in the right table. It indicated that two rows have been deleted. The statement returned the following message: 2 row(s) affected Code language: SQL (Structured Query Language) ( sql ) Note that you can nest a subquery inside another subquery with a certain depth. T1.id = 1 Code language: SQL (Structured Query Language) ( sql ) To create this query, it helps to list all the table to be joined so that you can see the relationship between them. The following statement deletes the row with id 1 in the t1 table and also row with ref 1 in the t2 table using DELETE.INNER JOIN statement: DELETE t1,t2 FROM t1 INSERT INTO t2( id, ref) VALUES( 'A', 1),( 'B', 2),( 'C', 3) Code language: SQL (Structured Query Language) ( sql ) Suppose, we have two tables t1 and t2 with the following structures and data: DROP TABLE IF EXISTS t1, t2 MySQL DELETE JOIN with INNER JOIN example The condition in the WHERE clause determine rows in the T1 and T2 that will be deleted. The expression T1.key = T2.key specifies the condition for matching rows between T1 and T2 tables that will be deleted. If you omit T1 table, the DELETE statement only deletes rows in T2 table. Similarly, if you omit T2 table, the DELETE statement will delete only rows in T1 table. Notice that you put table names T1 and T2 between the DELETE and FROM keywords. WHERE condition Code language: SQL (Structured Query Language) ( sql ) MySQL also allows you to use the INNER JOIN clause in the DELETE statement to delete rows from a table and the matching rows in another table.įor example, to delete rows from both T1 and T2 tables that meet a specified condition, you use the following statement: DELETE T1, T2 This tutorial introduces to you a more flexible way to delete data from multiple tables using INNER JOIN or LEFT JOIN clause with the DELETE statement. A single DELETE statement on multiple related tables which the child table have an ON DELETE CASCADE referential action for the foreign key.A single DELETE statement on multiple tables.In the previous tutorial, you learned how to delete rows of multiple tables by using: Always we need to use parenthesis in main query to define sub queries.įollowing is the syntax of using subqueries in sqlite main query.Summary: in this tutorial, we will show you how to delete data from multiple tables by using MySQL DELETE JOIN statement.We can use ORDER BY or BETWEEN clauses within the subqueries but it’s not possible to use ORDER BY or BETWEEN clauses in main query along with subqueries.In SQLite sub queries always return only one column and that column must match with the column mentioned in WHERE clause of main query.to compare result set values with table column values.įollowing are the basic rules which we need to follow while creating subqueries in SQLite. Mostly, in SQLite we use sub-queries with WHERE, EXISTS or IN operator along with comparison operators like >, <, =, etc. Generally, in SQLite we can use subqueries along with SELECT, UPDATE, INSERT and DELETE statements or inside of any subqueries based on our requirements. In SQLite sometimes we get requirements like need to compare one select statement result set with some other table column values in that case we will write queries within the query and we will call it as subqueries. Here we will learn SQLite subquery with example and how to use sqlite subqueries as nested queries or inner queries in select / where clause with examples.
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