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Can a blob have a default value?
1 Answer. BLOB , TEXT , GEOMETRY , and JSON columns cannot be assigned a default value.
What is the size of text in MySQL?
Maximum length for MySQL TEXT field types
| TINYTEXT | 256 bytes | |
|---|---|---|
| TEXT | 65,535 bytes | ~64kb |
| MEDIUMTEXT | 16,777,215 bytes | ~16MB |
| LONGTEXT | 4,294,967,295 bytes | ~4GB |
How do I change the default column value in MySQL?
To change a default value, use ALTER col_name SET DEFAULT : ALTER TABLE mytbl ALTER j SET DEFAULT 1000; Default values must be constants. For example, you cannot set the default for a date-valued column to NOW( ) , although that would be very useful.
Why does text column not have default value in MySQL?
If you try to create a TEXT column on a table, and give it a default value in MySQL, you get an error (on Windows at least). I cannot see any reason why a text column should not have a default value. No explanation is given by the MySQL documentation. It seems illogical to me (and somewhat frustrating, as I want a default value!).
Where are text blobs stored in MySQL?
But TEXT/BLOBS values are not stored directly in the record buffer used for reading/updating tables. So it is a bit more complex to assign default values for them. This is no definite answer, but at least a starting point for the why question.
How are text values represented in mysql table?
Each BLOB or TEXT value is represented internally by a separately allocated object. This is in contrast to all other data types, for which storage is allocated once per column when the table is opened. It seems like pre-filling these column types would lead to memory usage and performance penalties. Anybody know why this is not allowed?
Why does MySQL V5 throw an error but Linux only raises a warning?
Windows MySQL v5 throws an error but Linux and other versions only raise a warning. This needs to be fixed. WTF? On MS Windows the “no DEFAULT” rule is an error, while on other platforms it is often a warning. While not a bug, it’s possible to get trapped by this if you write code on a lenient platform, and later run it on a strict platform: