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18 mar 2014 · We can use CASE for setting blank value to some char or String. I am using NA as Default string. SELECT phone, CASE WHEN phone2 = '' THEN 'NA' END AS phone2 ELSE ISNULL(phone2,0) FROM jewishyellow.users WHERE phone LIKE '813%'
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
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.
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.
26 kwi 2023 · The WHERE clause is a critical part of any MySQL query because it allows you to filter the data in your tables based on specified criteria. The syntax of the WHERE clause is as follows: SELECT column1, column2, ... FROM table_name. WHERE condition;
An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and functions involved in the expression. All columns in the following example return NULL: mysql> SELECT NULL, 1+NULL, CONCAT('Invisible',NULL);
