1.sysdate

-- oracle
SELECT SYSDATE FROM DUAL

-- mysql
 SELECT SYSDATE() FROM DUAL

--  sentence 3
SELECT SYSDATE() , LNS_END_DATE,SYSDATE() - LNS_END_DATE FROM MRS_CUST_LNS_DUE 

--  sentence 4
SELECT CURDATE() , DATE(LNS_END_DATE),CURDATE() - DATE(LNS_END_DATE) FROM MRS_CUST_LNS_DUE 

The above sentence 3 The result is wrong , Need to change to a statement 4 Can only be

2. Line number problem

MYSQL No, rowner function

-- mysql The sentence used is :
 SELECT B.content  FROM
  ( SELECT T.content FROM T1 T  WHERE T.text_type = 1 ORDER BY T.gmt_create desc   )  B   LIMIT 4

-- oracle The sentence is :
 SELECT content  FROM
  ( SELECT T.content FROM T1 T   WHERE T.text_type = 1 ORDER BY T.gmt_create desc  )   WHERE ROWNER <4

3. Date question TRUNC An alternative

-- ORACLE
--  Get the first day of the month  TRUNC
		SELECT T2.BRANCH_NAME, T3.PROD_NAME,SUM(T1.VALID_NUM) C
		FROM MRS_ELCT_SUMMARY T1
		LEFT JOIN MRS_BRANCH T2 ON T1.BRANCH_ID = T2.ID
		LEFT JOIN MRS_ELCT_PRODUCT T3 ON T1.PRODUCT_ID = T3.ID
		WHERE  TRUNC(T1.DATA_DATE,'mm') = TRUNC(SYSDATE,'mm')
		GROUP BY T2.BRANCH_NAME, T3.PROD_NAME;

--MYSQL  No, TRUNC function , The meaning of the equality of year and month is the same as that of the first day of a certain year and month 
		SELECT T2.BRANCH_NAME, T3.PROD_NAME,SUM(T1.VALID_NUM) C
		FROM MRS_ELCT_SUMMARY T1
		LEFT JOIN MRS_BRANCH T2 ON T1.BRANCH_ID = T2.ID
		LEFT JOIN MRS_ELCT_PRODUCT T3 ON T1.PRODUCT_ID = T3.ID
		WHERE date_format(T1.DATA_DATE, '%Y%m') = date_format(CURDATE(), '%Y%m')
		GROUP BY T2.BRANCH_NAME, T3.PROD_NAME