Solution to the Failure of Converting the Field Type

Scenario

The varchar field is read using the char data type, and cannot be converted through the char() function.

Fault Analysis

The char() function cannot be used to convert data types.

Solution

The CAST() function and CONVERT() function of RDS for MySQL can be used to obtain values of one type and generate values of another type. The syntax is as follows:

CAST(value as type);
CONVERT(value, type);

That is, CAST(xxx AS type) and CONVERT(xxx, type).

The data types that can be converted are limited. The supported data types are as follows:

• BINARY: the same as adding a binary prefix to a data string
• CHAR(): characters. You can specify the length of the characters.
• DATE: calendar date
• Time: time of day
• DATETIME: date and time
• DECIMAL: floating point number
• SIGNED: integer
• UNSIGNED: unsigned integer