Cast int to varchar

Question

I have below query and need to cast id to varchar

Schema

create table t9 (id int, name varchar (55)); insert into t9( id, name)values(2, 'bob'); 

What I tried

select CAST(id as VARCHAR(50)) as col1 from t9;  select CONVERT(VARCHAR(50),id) as colI1 from t9; 

but they don't work. Please suggest.

Answer 1

You will need to cast or convert as a CHAR datatype, there is no varchar datatype that you can cast/convert data to:

select CAST(id as CHAR(50)) as col1  from t9;  select CONVERT(id, CHAR(50)) as colI1  from t9; 

See the following SQL — in action — over at SQL Fiddle:

/*! Build Schema */ create table t9 (id INT, name VARCHAR(55)); insert into t9 (id, name) values (2, 'bob');  /*! SQL Queries */ select CAST(id as CHAR(50)) as col1 from t9; select CONVERT(id, CHAR(50)) as colI1 from t9; 

Besides the fact that you were trying to convert to an incorrect datatype, the syntax that you were using for convert was incorrect. The convert function uses the following where expr is your column or value:

 CONVERT(expr,type) 

or

 CONVERT(expr USING transcoding_name) 

Your original query had the syntax backwards.

Answer 2

You're getting that because VARCHAR is not a valid type to cast into. According to the MySQL docs (http://dev.mysql.com/doc/refman/5.5/en/cast-functions.html#function_cast) you can only cast to:

• BINARY[(N)]
• CHAR[(N)]
• DATE
• DATETIME
• DECIMAL[(M[,D])]
• SIGNED
• [INTEGER]
• TIME
• UNSIGNED [INTEGER]

I think your best-bet is to use CHAR.