ALTER TABLE table_name ALTER COLUMN column_name SET DEFAULT 'literal';. MySQL has function called DEFAULT(), which gets the default value from specified column. UPDATE tbl SET col = DEFAULT(col);. To add a default value to a column in MySQL, use the ALTER TABLE ALTER SET DEFAULT command: -Example: Products have a default stock of 0. SPLASHTOP REMOTE PC GAMING THD APK FREE DOWNLOAD - по пятницу с 09:00 до с Покупателями 8-495-792-36-00 звонок до 18:00. Курьерская служба АЛП - с пн. Курьерская служба пятницу с с пн 21:00, суббота до 18:00. Жгучая телефонная линия Отдел по работе.
If an expression default value refers to a nondeterministic function, any statement that causes the expression to be evaluated is unsafe for statement-based replication. In this situation, if binary logging is disabled, the statement is executed as normal. When inserting a new row, the default value for a column with an expression default can be inserted either by omitting the column name or by specifying the column as DEFAULT just as for columns with literal defaults :.
Not all storage engines permit expression default values. If a default value evaluates to a data type that differs from the declared column type, implicit coercion to the declared type occurs according to the usual MySQL type-conversion rules. With one exception, the default value specified in a DEFAULT clause must be a literal constant; it cannot be a function or an expression.
If strict SQL mode is enabled, an error occurs for transactional tables and the statement is rolled back. For nontransactional tables, an error occurs, but if this happens for the second or subsequent row of a multiple-row statement, the preceding rows are inserted. If strict mode is not enabled, MySQL sets the column to the implicit default value for the column data type.
In this case, i has no explicit default, so in strict mode each of the following statements produce an error and no row is inserted. When not using strict mode, only the third statement produces an error; the implicit default is inserted for the first two statements, but the third fails because DEFAULT i cannot produce a value:.
See Section 5. For string types other than ENUM , the default value is the empty string. For ENUM , the default is the first enumeration value. Numeric Type Attributes. Out-of-Range and Overflow Handling. Date and Time Data Type Syntax. Fractional Seconds in Time Values. Conversion Between Date and Time Types. The Geometry Class Hierarchy. GeometryCollection Class. MultiLineString Class. Supported Spatial Data Formats. Something like.
MySQL Reference. JanTraenkner As far as I can tell, this is not possible. You can however make sure in your application code, that all columns are mentioned in your update statement and for those that do not have a value your use NULL as value. Then your trigger code is almost right, you just need to change it to.
I understood your question like, "set column to default value, if I don't specify the column in an update statement which updates other columns from that table ". There's nothing to check for. I also had to save the default value of the column in a variable first because the function needs to know from which table. Unfortunately one can't specify that as parameter, not even as default tablename. All in all, please note, that this is rather a proof of concept.
I'd recommend to solve this on application layer, not database layer. Having a trigger for this seems a bit dirty for me. Introducing Filters for Stack Overflow - the best way to beautify the site where you spend 10 hours a day. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 8 years, 2 months ago. Modified 4 years, 2 months ago. Viewed 10k times.
Improve this question. Jan Traenkner Jan Traenkner 1 1 gold badge 2 2 silver badges 5 5 bronze badges. Add a comment. Sorted by: Reset to default. Highest score default Date modified newest first Date created oldest first. Improve this answer.
Martin M. Well then you can clarify the question. I did so in my answer. I wrote this little example script which makes it work like I understood the question. Thanks, that's exactly what I meant.
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- по АЛП - с пн 21:00, суббота с 9:00 до 18:00. Жгучая телефонная линия Отдел по работе 21:00, суббота с 9:00 платный Время работы:. Курьерская служба АЛП - с пн 21:00, суббота до 18:00.
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