■システム日付
■外部結合
・Oracle SYSDATE ・MySQL NOW()■日付型→文字列型変換(YYYY/MM/DD)
・Oracle: TO_DATE(TO_CHAR(SYSDATE), 'YY-MM-DD') ・MySQL: DATE_FORMAT( SYSDATE() , '%Y-%m-%d')■TRUNC(日付)
・Oracle TRUNC(SYSDATE) ・MySQL DATE(SYSDATE())■ADD_MONTH
・Oracle ADD_MONTHS(SYSDATE, 1) ・MySQL DATE_ADD(SYSDATE(),INTERVAL 1 MONTH)■MONTHS_BETWEEN
・Oracle MONTHS_BETWEEN(SYSDATE, SYSDATE+1) ・MySQL DATEDIFF(SYSDATE(), SYSDATE()+1)■TO_NUMBER
・Oracle
TO_NUMBER('-100')
・MySQL
CAST('-0008000' as signed)
■TO_DATE・Oracle
TO_DATE('9999/12/31', 'YYYY/MM/DD')
・MySQL
STR_TO_DATE('9999/12/31', '%Y/%m/%d')
■NULL文字変換・Oracle: NVL(exp1,exp2) ・MySQL: IFNULL(exp1, exp2)
■外部結合
・Oracle:
WHERE
A.id(+) = B.id
・MySQL:
FROM A
RIGHT OUTER JOIN B
ON (A.id = B.id)
・Oracle:
WHERE
A.id = B.id(+)
・MySQL:
FROM A
LEFT OUTER JOIN B
ON (A.id = B.id)