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29 lis 2019 · If you simply want to check if a column is null or empty, you may be better off doing this: SELECT myCol FROM MyTable WHERE MyCol IS NULL OR MyCol = '' See TRIM COALESCE and IS NULL for more info. Also Working with null values from the MySQL docs
31 maj 2013 · For DBMSs that treat '' as a value (not null), Vinko's query works: select name,age from members where name is not null and name <> ''. For Oracle, which treats '' as a null, tha above doesn't work but this does: select name,age from members where name is not null.
6 cze 2024 · We can use the function NULLIF to compare and check if the column contains null or empty values: SELECT id, name FROM Department WHERE NULLIF(TRIM(code), '') IS NULL; The NULLIF function evaluates its two arguments, returning NULL if they are equal.
21 cze 2024 · The WHERE clause is used to specify a condition while fetching data from a single table or by joining multiple tables. Only the records that meet the specified condition are retrieved. Syntax: SELECT column1, column2, ... FROM table_name.
I tried the following: SELECT column_name. FROM information_schema.columns. WHERE table_name = "table_name". AND EXISTS (. SELECT DISTINCT column_name FROM table_name WHERE column_name IS NOT NULL. ) But this also returns the column names where all the entries are NULL.
This tutorial shows you how to use MySQL WHERE clause to filter rows based on specified conditions.
The MySQL WHERE Clause. The WHERE clause is used to filter records. It is used to extract only those records that fulfill a specified condition. WHERE Syntax. SELECT column1, column2, ... FROM table_name. WHERE condition; Note: The WHERE clause is not only used in . SELECT statements, it is also used in UPDATE, DELETE, etc.! Demo Database.
