Re: How to implent CONVERT ( data_type [ ( length ) ] , expression ) function in postgreSQL

On Sun, Nov 2, 2014 at 3:40 PM, rohtodeveloper <rohtodeveloper(at)outlook(dot)com>
wrote:

>
> Dear
>
>
> In SQLServer, there'are two functions to converte an expression of one
> data type to another.
>
> 1. CAST ( expression AS data_type [ ( length ) ] )
> 2. CONVERT ( data_type [ ( length ) ] , expression )
>
> However, In PostgreSQL, there's only the CAST ( expression AS data_type [
> ( length ) ] ) function. I have tried the following two ways to implenting
> the CONVERT ( data_type [ ( length ) ] , expression ) function, but both
> are failed.
>
> 1. CREATE FUNCTION .....
> The function's arguments can only be expressions but not data_type .
> 2. Modifying the gram.y .....
> The CONVERT ( data_type [ ( length ) ] , expression ) is in grammer
> conflict with the PostgreSQL self's
> convert(data,src_encoding_name,dest_encoding_name) function. And the
> PostgreSQL self's convert(data,src_encoding_name,dest_encoding_name)
> function cannot be used.
>
> I wonder whether there's a better way to solve this problem.
> Any help will be appreciated.
> Please do not cross post to multiple lists.
>
>

Please do not cross post to various lists.

For the options you suggested:

1) Pass in datatype as string and deparse and process in the function.
2) Are you referring to pg_convert here?

IMO I do not understand why you need the convert function in the first
place. You may want to refer to
http://www.postgresql.org/docs/9.3/static/typeconv.html