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24 sty 2013 · A column can only return one data type - DATETIME != string/VARCHAR. If you want a zero length string in the event of the value being NULL, you have to explicitly change the data type, using CAST/CONVERT to change the non-NULL value to a VARCHAR/etc data type.
28 gru 2010 · To get all rows wtih an empty datetime column you could do this: SELECT * FROM yourtable WHERE yourdatecolumn IS 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.
What is a NULL Value? A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field. Then, the field will be saved with a NULL value.
In MySQL, 0 or NULL means false and anything else means true. The default truth value from a boolean operation is 1. NULL instead of death <>. NULL. Two NULL values are regarded as equal in a GROUP BY. When doing an ORDER BY, NULL values are presented first if you do ORDER BY ... ASC and last if you do ORDER BY ...
17 lis 2015 · If you're checking whether or not the value is NULL, there is no need to convert it to a date, unless you wanted to return a date value (which you don't seem to). Instead, use: SELECT ISNULL( DOB , '') Which will return '' if the value is NULL. A NULL date is NULL (no value).
27 lut 2007 · My problem is with dates. Since there is no such thing as a 'blank' date field, I have to allow nulls on date columns. Using some arbitrary default (01/01/1900) is unacceptable since this could...
