Oracle SQL Experts: How to select UNIQUE records from a table using a SQL Query

DROP TABLE T_UNIQUE;

CREATE TABLE T_UNIQUE (

ID NUMBER(6,0),

NAME VARCHAR2(20),

SAL NUMBER(10));

INSERT INTO T_UNIQUE(ID,NAME,SAL) VALUES(100,'RAVI',2100);

INSERT INTO T_UNIQUE(ID,NAME,SAL) VALUES(101,'SCOTT',3100);

INSERT INTO T_UNIQUE(ID,NAME,SAL) VALUES(102,'CLARK',4100);

INSERT INTO T_UNIQUE(ID,NAME,SAL) VALUES(103,'DAVIS',51000);

COMMIT;

SELECT * FROM T_UNIQUE;

Using ROW_NUMBER

STEP 1:

SELECT ID,NAME,SAL,

ROW_NUMBER() OVER(PARTITION BY ID,NAME,SAL ORDER BY ID) AS RN

FROM T_UNIQUE;

STEP 2:

SELECT ID, NAME, SAL FROM(

SELECT ID,NAME,SAL,

ROW_NUMBER() OVER(PARTITION BY ID,NAME,SAL ORDER BY ID) AS RN

FROM T_UNIQUE)

WHERE RN = 1;

ID NAME SAL

---------- -------------------- ----------

100 RAVI 2100

101 SCOTT 3100

102 CLARK 4100

103 DAVIS 51000

Using GROUP BY

SELECT ID,NAME,SAL FROM T_UNIQUE