问题
I have 2 tables and need to get result on brand code.
In the database i have for example 2 different brands but their code is the same (only difference in lower and upper case). For example:
code Name ab Nike AB Adidas
How to inner join 2 tables on code to get this 2 separately?
Right now after inner join i get total sum of this 2.
SELECT Code, BrandName, Count(*) QTY, SUM(Price) TOTAL
FROM A
INNER JOIN B
ON A.Code=B.Code
GROUP BY Code, BrandName
This query will give me wrong result as it does not join sensitively on upper and lower case.
Please help :)
回答1:
There are at least two quick ways you can solve this.
1. You specify a case-sensitive collation (rules for comparing strings across characters in a character set) for A.Code and B.Code. In MySQL and a few other database management systems, the default collation is case-insensitive.
That is, assuming that you're using MySQL or similar, you'll have to modify your statement as such:
SELECT Code, BrandName, Count(*) QTY, SUM(Price) TOTAL
FROM A
INNER JOIN B
ON A.Code=B.Code COLLATE latin1_bin
GROUP BY Code, BrandName
If, however, you plan on only performing case-sensitive queries on A and B, it may be in your interest to set the default collation on those two tables to case-sensitive.
Please see How can I make SQL case sensitive string comparison on MySQL?
2. Cast A.Code and B.Code to a binary string and compare the two. This is an simple way to compare two strings, byte-by-byte, thus achieving case-insensitivity.
SELECT Code, BrandName, Count(*) QTY, SUM(Price) TOTAL
FROM A
INNER JOIN B
ON BINARY A.Code=B.Code
GROUP BY Code, BrandName
回答2:
Since you use a collation that is case insensitive and want to differentiate on case try using the collate keyword with a suitable case-sensitive collation:
INNER JOIN B
ON A.Code COLLATE Latin1_General_CS_AS_KS_WS = B.Code COLLATE Latin1_General_CS_AS_KS_WS
来源：https://stackoverflow.com/questions/29533346/join-2-tables-case-sensitive-upper-and-lower-case