You need to be aware of the issues when sorting and comparing DBCS text, because the Option Compare Text statement has a special behavior when used on DBCS strings. When you use the Option Compare Binary statement, comparisons are made according to a sort order derived from the internal binary representations of the characters. When you use Option Compare Text statement, comparisons are made according to the case-insensitive textual sort order determined by the user's system locale.
In English "case-insensitive" means ignoring the differences between uppercase and lowercase. In a DBCS environment, this has additional implications. For example, some DBCS character sets (including Japanese, Traditional Chinese, and Korean) have two representations for the same character: a narrow-width letter and a wide-width letter. For example, there is a single-byte "A" and a double-byte "A." Although they are displayed with different character widths, Option Compare Text treats them as the same character. There are similar rules for each DBCS character set.
You need to be careful when you compare two strings. Even if the two strings are evaluated as the same using Like or StrComp, the exact characters in the strings can be different and the string length can be different, too.
For More Information For general information about comparing strings with the Option Compare statement, see "International Sort Order and String Comparison."