Converting Integers to Strings in SQL
Issue
Attempting to directly cast an integer (INT) column to a VARCHAR data type in SQL might fail, depending on the specific database system. Many SQL dialects don't directly support VARCHAR as a target type for this kind of conversion.
Example of an unsuccessful attempt:
SELECT CAST(id AS VARCHAR(50)) AS col1 FROM t9; SELECT CONVERT(VARCHAR(50), id) AS col1 FROM t9;
Resolution
The solution involves casting the INT to a CHAR data type instead of VARCHAR. This approach is generally more compatible across various SQL databases.
Corrected query:
SELECT CAST(id AS CHAR(50)) AS col1 FROM t9; SELECT CONVERT(id, CHAR(50)) AS col1 FROM t9;
Note that the CONVERT
function syntax was also slightly incorrect in the original example. The correct syntax is either:
CONVERT(expr, type)
or
CONVERT(expr USING transcoding_name)
where expr
represents the column or value to be converted, and type
specifies the target data type. The USING transcoding_name
variant is used for character set conversions.
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