问题
I am new to the SQL express server and trying to convert HEX to bigint and bigint to HEX again. However, I noticed that MySQL and SQL express server calculations give different results.
HEX to bigint:
MySQL:
SELECT CONV('DA346CC793AD1510',16,10);
Output:
15723311803489129744
SQL Express :
SELECT CAST(CONVERT(VARBINARY(MAX), 'DA346CC793AD1510', 2) AS BIGINT);
Output:
-2723432270220421872
Why MySQL and SQL express servers give different outputs? From a mathematical point of view, it must be the same.
However, bigint to HEX conversion in both MySQL and the SQL express servers give the same result.
MySQL: select conv(column_name,10,16);
SQL Express select FORMAT(column_name,'X');
What is the right way in the SQL express server to convert HEX to bigint and bigint to HEX? Am I missing something?
回答1:
"Why MySQL and SQL express servers give different outputs? From a mathematical point of view, it must be the same."
BIGINT upper range is 2 to power 63 - 1:
9,223,372,036,854,775,807 -- upper range of BIGINT
15,723,311,803,489,129,744 -- converted "DA346CC793AD1510" value
BIGINT cannot store such value and simply overflows:
9,223,372,036,854,775,807 -> (overflow) -> starting from the lowest value (-9,223,372,036,854,775,808) + (15,723,311,803,489,129,744 - 9,223,372,036,854,775,807) -> -2,723,432,270,220,421,872
来源：https://stackoverflow.com/questions/61746221/mysql-vs-sql-express-server-hex-bigint-and-bigint-hex-conversion