A multi-Table query SQL statement

Table 1: Table 2:
Id info id value
1 a 1 10
2 B 2 30
3 c
4 d

Want to get
Id value
1 10 // Table 2 exists
2 20 // Table 2 exists
3 0 // Table 2 does not exist
4 0 // Table 2 does not exist
Whether an SQL statement can be used to solve the problem, instead of obtaining the id from table 1 first, and then finding whether the record exists in Table 2. If yes, it is read directly, if not, the value is 0.

Copy codeThe Code is as follows:
Select Table 1.id, isnull (value, 0) from table 1
Left join table 2
On Table 1.id= table 2.id
 



 Copy codeThe Code is as follows:
Select a. id, isnull (B. value, 0) from table 1
Left join Table 2 B
On a. id = B. id