SQL Left Join
1.LEFT JOIN returns:
-
A. All rows from right table
-
B. Matching rows only
-
C. All rows from left + matched from right
-
D. All rows with NULLs
All rows from left + matched from right
All rows from left + matched from right
2.In LEFT JOIN, if no match is found on the right table, the result is:
-
A. Deleted
-
B. Default value
-
C. NULL for right table columns
-
D. 0
NULL for right table columns
NULL for right table columns
3.LEFT JOIN is also called:
-
A. OUTER LEFT
-
B. LEFT OUTER JOIN
-
C. LEFT INNER JOIN
-
D. RIGHT OUTER JOIN
LEFT OUTER JOIN
LEFT OUTER JOIN
4.Which is correct?
-
A. SELECT * FROM A LEFT JOIN B ON A.id = B.id;
-
B. SELECT * FROM A LEFT OUTER JOIN B ON A.id = B.id;
-
C. Both A and B
-
D. Neither
Both A and B
Both A and B
5.If A has 3 rows and B has 0 rows, how many rows will LEFT JOIN return?
-
A. 0
-
B. 1
-
C. 3
-
D. Error
3
3