New string conversion functions

SQL Server 2012 contains two new string conversion functions. PARSE and TRY_PARSE. These two functions make life a lot easier when you want to convert a string to another data type.

The different between the two functions are that PARSE will return an error if the conversion fails. TRY_PARSE will return NULL.

Some examples:

/* Returns the same results */
SELECT PARSE('28 dec 1977' AS date)
SELECT TRY_PARSE('28 dec 1977' AS date)

/* PARSE will return the error
   Error converting string value '30 feb 1977' into data type date using culture  */
SELECT PARSE('30 feb 1977' AS date)
SELECT TRY_PARSE('30 feb 1977' AS date)

It is possible to tell PARSE and TRY_PARSE if your input string-date is formatted in another regional setting ex. month day year.

/* Returns the same result 3th may 1977 */
SELECT TRY_PARSE('03-05-1977' AS date USING 'da-DK') AS Result
SELECT TRY_PARSE('05-03-1977' AS date USING 'en-US') AS Result

Finally an example on how to convert a string to an tinyint.

/* The last TRY_PARSE return NULL while 2222 is larger than TINYINT */

SELECT TRY_PARSE('22'AS int)
SELECT TRY_PARSE('2222'AS tinyint)

In some cases the right thing to do is to raise an error. In that case use PARSE. In most cases I think I’ll go with TRY_PARSE.