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1 lut 2010 · Here's a query to update a table based on a comparison of another table. If record is not found in tableB, it will update the "active" value to "n". If it's found, will set the value to NULL. UPDATE tableA LEFT JOIN tableB ON tableA.id = tableB.id SET active = IF(tableB.id IS NULL, 'n', NULL)"; Hope this helps someone else.
29 kwi 2015 · IF EXISTS (select * from users where username = 'something') THEN. update users set id= 'some' where username = 'something'; ELSE. insert into users (username) values ('something'); END IF; end $$. delimiter ; and call it like this: call select_or_insert();
For example, if the table contains 1 and 2 in the id column and 1 is updated to 2 before 2 is updated to 3, an error occurs. To avoid this problem, add an ORDER BY clause to cause the rows with larger id values to be updated before those with smaller values: UPDATE t SET id = id + 1 ORDER BY id DESC;
In this article, we would like to show you UPDATE query with IF condition in MySQL. Quick solution: UPDATE `table_name` SET `column_name` = IF(condition , if_true, if_false); Practical example. To show UPDATE query with IF condition, we will use the following users table:
The UPDATE statement is used to modify the existing records in a table. UPDATE Syntax. UPDATE table_name. SET column1 = value1, column2 = value2, ... WHERE condition; Note: Be careful when updating records in a table! Notice the . WHERE clause in the UPDATE statement. The WHERE clause specifies which record (s) that should be updated.
15 mar 2013 · I'm trying to figure out how to mass update a mysql table based on if a value exists in a column in another table. e.g. pseudo code: if Table1.`col`=Table2.`col` then. Update Table1.`status`=1. or. if table2.`col` exists in table1.`col` Update Table1.`status`=1. What's the best way to achieve this? mysql. sql. asked Aug 2, 2011 at 7:05.
First, specify the table that you want to update after the UPDATE keyword (T1). Second, use either INNER JOIN or LEFT JOIN and a join predicate. The JOIN clause must appear right after the UPDATE clause. Third, assign new values to the columns of the T1 table that you want to update data.
