Mysql：函數之一：information functions

Name	Description
BENCHMARK(cont,expr)	Repeatedly execute an expression主要是測試計算密集型的標量運算式——類似於壓力測試。如果是查詢，必須單行單列
CHARSET(str)(v4.1.0)	Return the character set of the argument
COERCIBILITY(str)(v4.1.1)	Return the collation coercibility value of the string argument
COLLATION(str)(v4.1.0)	Return the collation of the string argument
CONNECTION_ID()	Return the connection ID (thread ID) for the connection串連的會話或線程ID
CURRENT_USER(), CURRENT_USER	Return the user name and host name combination從mysql伺服器帳號管理中獲得的對應當前會話使用者的真實登入認證使用者，兩者可能不同。該函數是和特定的安全上下文相關的！如果sqlserver的current_user()——隨調用的安全上下文變化可能和登入的user()、許可權都不相同
DATABASE()、SCHEMA()(v5.0.2)	Return the default (current) database name當前資料庫，可能是null
FOUND_ROWS()	For a SELECT with a LIMIT clause, the number of rows that would be returned were there no LIMIT clause select語句查詢到合格行數——該函數會忽略limit子句的影響
LAST_INSERT_ID()	Value of the AUTOINCREMENT column for the last INSERT
ROW_COUNT()(v5.0.1)	returns the number of rows updated, inserted, or deleted by the preceding statement. This is the same as the row count that the mysql client displays and the value from the mysql_affected_rows() C API function.和sqlserver的@@rowcount對應
USER()、SYSTEM_USER()、SESSION_USER()	Return the current user name and host name是從真實的串連環境中獲得的完全限定使用者名稱，與真實的登入認證使用者可能不同。
VERSION()	Returns a string that indicates the MySQL server version