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Dear I'm doing a job about converting an _expression_ of one data type to another. In SQLServer, there'are two functions to do this job. 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. Best Regards Rohtodeveloper |
