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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.
11 kwi 2019 · I need to do and IF/THEN statement in mysql based on whether a value exists in a column. If it exists, I need to perform an update on the record and if it does not, then an error should be thrown. I want to check that the siteID actually exists. How can I add an "IF EXISTS" statement?
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.
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);
13 mar 2021 · UPDATE Readings Act, LATERAL (SELECT Reading FROM Readings WHERE SystemID = Act.SystemID AND ReadingDate < Act.ReadingDate AND Reading IS NOT NULL ORDER BY SystemID, ReadingDate DESC LIMIT 1) Prev SET Act.Reading = IF(Act.Reading IS NULL, Prev.Reading, Act.Reading), Act.Diff = CASE WHEN Act.Reading IS NULL THEN 0 ELSE Act.Reading - Prev.Reading ...
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();
22 sty 2018 · IF EXISTS(SELECT * FROM weatherbyday WHERE DATE(DateTime) = CURDATE()) THEN update weatherbyday SET TempMin='[th0temp-dmin]', TempMax='[th0temp-dmax]' WHERE DATE(DateTime) = CURDATE() ELSE INSERT INTO weatherbyday (DateTime, TempMin, TempMax ) VALUES ('[YYYY]-[MM]-[DD] [hh]:[mm]:[ss]', '[th0temp-dmin]','[th0temp-dmax]' )
