Mixing
SQL Server - Join only when the condition is number
I have a table EmployeeLeave
CREATE TABLE EmployeeLeave (
EmployeeId INT,
LeaveType VARCHAR()
);
LeaveType can have numbers as well as string.
CREATE TABLE MST_LeaveReason (
ReasonId INT,
Reason VARCHAR()
);
SELECT * FROM EmployeeLeave EL
LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType
Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.
Thanks in advance.
sql
sql-server join asked Nov 22 '18 at 11:46
ErmaErma
104313
add a comment |
I have a table EmployeeLeave
CREATE TABLE EmployeeLeave (
EmployeeId INT,
LeaveType VARCHAR()
);
LeaveType can have numbers as well as string.
CREATE TABLE MST_LeaveReason (
ReasonId INT,
Reason VARCHAR()
);
SELECT * FROM EmployeeLeave EL
LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType
Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.
Thanks in advance.
sql
sql-server join asked Nov 22 '18 at 11:46
ErmaErma
104313
If yourvarcharis only going to have a length of 1, why not usechar(1)and save the overhead of having a "variable" length?
– Larnu
Nov 22 '18 at 11:48
@Larnu:VARCHAR()is (fortunately?) not legal syntax. It's probably not shorthand forVARCHAR-with-no-length-which-is-implicitly-1 in this case.
– Jeroen Mostert
Nov 22 '18 at 11:51
add a comment |
I have a table EmployeeLeave
CREATE TABLE EmployeeLeave (
EmployeeId INT,
LeaveType VARCHAR()
);
LeaveType can have numbers as well as string.
CREATE TABLE MST_LeaveReason (
ReasonId INT,
Reason VARCHAR()
);
SELECT * FROM EmployeeLeave EL
LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType
Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.
Thanks in advance.
sql
sql-server join asked Nov 22 '18 at 11:46
ErmaErma
104313
I have a table EmployeeLeave
CREATE TABLE EmployeeLeave (
EmployeeId INT,
LeaveType VARCHAR()
);
LeaveType can have numbers as well as string.
CREATE TABLE MST_LeaveReason (
ReasonId INT,
Reason VARCHAR()
);
SELECT * FROM EmployeeLeave EL
LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType
Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.
Thanks in advance.
sql
sql-server join sql
sql-server join asked Nov 22 '18 at 11:46
ErmaErma
104313
asked Nov 22 '18 at 11:46
ErmaErma
104313
asked Nov 22 '18 at 11:46
ErmaErma
104313
asked Nov 22 '18 at 11:46
ErmaErma
104313
asked Nov 22 '18 at 11:46
ErmaErma
104313
104313
If yourvarcharis only going to have a length of 1, why not usechar(1)and save the overhead of having a "variable" length?
– Larnu
Nov 22 '18 at 11:48
@Larnu:VARCHAR()is (fortunately?) not legal syntax. It's probably not shorthand forVARCHAR-with-no-length-which-is-implicitly-1 in this case.
– Jeroen Mostert
Nov 22 '18 at 11:51
add a comment |
If yourvarcharis only going to have a length of 1, why not usechar(1)and save the overhead of having a "variable" length?
– Larnu
Nov 22 '18 at 11:48
@Larnu:VARCHAR()is (fortunately?) not legal syntax. It's probably not shorthand forVARCHAR-with-no-length-which-is-implicitly-1 in this case.
– Jeroen Mostert
Nov 22 '18 at 11:51
If your
varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?– Larnu
Nov 22 '18 at 11:48
If your
varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?– Larnu
Nov 22 '18 at 11:48
@Larnu:
VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.– Jeroen Mostert
Nov 22 '18 at 11:51
@Larnu:
VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.– Jeroen Mostert
Nov 22 '18 at 11:51
add a comment |
1 Answer
1
active
oldest
votes
Use try_convert():
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);
You can also do this in the other direction:
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;
Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Use try_convert():
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);
You can also do this in the other direction:
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;
Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
add a comment |
Use try_convert():
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);
You can also do this in the other direction:
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;
Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
add a comment |
Use try_convert():
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);
You can also do this in the other direction:
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;
Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
Use try_convert():
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);
You can also do this in the other direction:
SELECT *
FROM EmployeeLeave EL LEFT JOIN
MST_LeaveReason LR
ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;
Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
answered Nov 22 '18 at 11:48
Gordon LinoffGordon Linoff
781k35310414
781k35310414
add a comment |
add a comment |
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If your
varcharis only going to have a length of 1, why not usechar(1)and save the overhead of having a "variable" length?– Larnu
Nov 22 '18 at 11:48
@Larnu:
VARCHAR()is (fortunately?) not legal syntax. It's probably not shorthand forVARCHAR-with-no-length-which-is-implicitly-1 in this case.– Jeroen Mostert
Nov 22 '18 at 11:51