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[AliasFunction] Add support for cast in alias function (#6754)

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support #6753
This commit is contained in:
qiye
2021-10-10 23:05:44 +08:00
committed by GitHub
parent 0941322dd6
commit 675aef7d75
12 changed files with 415 additions and 20 deletions
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9
docs/en/sql-reference/sql-statements/Data Definition/create-function.md
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@ -47,8 +47,8 @@ CREATE [AGGREGATE] [ALIAS] FUNCTION function_name
>
> `Function_name`: To create the name of the function, you can include the name of the database. For example: `db1.my_func'.
>
> `arg_type`: The parameter type of the function is the same as the type defined at the time of table building. Variable-length parameters can be represented by `,...`. If it is a variable-length type, the type of the variable-length part of the parameters is the same as the last non-variable-length parameter type.
> **NOTICE**: `ALIAS FUNCTION` variable-length parameters are not supported, and there is at least one parameter.
> `arg_type`: The parameter type of the function is the same as the type defined at the time of table building. Variable-length parameters can be represented by `,...`. If it is a variable-length type, the type of the variable-length part of the parameters is the same as the last non-variable-length parameter type.
> **NOTICE**: `ALIAS FUNCTION` variable-length parameters are not supported, and there is at least one parameter. In particular, the type `ALL` refers to any data type and can only be used for `ALIAS FUNCTION`.
>
> `ret_type`: Required for creating a new function. This parameter is not required if you are aliasing an existing function.
>
@ -130,8 +130,13 @@ If the `function_name` contains the database name, the custom function will be c
5. Create a custom alias function
```
-- create a custom functional alias function
CREATE ALIAS FUNCTION id_masking(INT) WITH PARAMETER(id)
AS CONCAT(LEFT(id, 3), '****', RIGHT(id, 4));
-- create a custom cast alias function
CREATE ALIAS FUNCTION decimal(ALL, INT, INT) WITH PARAMETER(col, precision, scale)
AS CAST(col AS decimal(precision, scale));
```
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