Character String Literal Evaluation Examples

MySQL Tutorials - Herong's Tutorial Examples

∟Character String Literal Evaluation Examples

This section provides tutorial examples on how character string literals are evaluated to values of different datatypes.

Character string literal evaluation example - CharStringLiterals.sql:

-- CharStringLiterals.sql
-- Copyright (c) 1999 HerongYang.com. All Rights Reserved.
--
SELECT 'Hello world!' AS LINE_1;
SELECT 'Loews L''Enfant Plaza' AS LINE_2;
SELECT '123'+ 0 AS LINE_3;
SELECT '0.123e-1' + 0 AS LINE_4;
SELECT 'ABC' + 1 AS LINE_5;

Output on MySQL server 8.0:

herong> set mysql="\Program Files\MySQL\MySQL Server 8.0"

herong> %mysql%\bin\mysql --user=root --password=TopSecret \
   < CharStringLiterals.sql

LINE_1
Hello world!
LINE_2
Loews L'Enfant Plaza
LINE_3
123
LINE_4
0.0123
LINE_5
1

Note that:

Line 2 shows that "''" is evaluated as "'" in a string expression.
Line 4 confirms that a character string literal can be evaluated to an approximate number in a numeric expression.
Line 5 confirms that a character string literal will be evaluated to 0, if the string is an invalid numeric literal.