SSIS派生列表示

Question

I have below derived expression for timestamp in SSIS

(DT_DBTIME)(SUBSTRING([Column 11],1,2) + ":" + SUBSTRING([Column 11],3,2) + ":" + SUBSTRING([Column 11],5,2)) 

but it's not taking null values so I tried this one

ISNULL ( [Column 11] ) ? "000000" : (DT_DBTIME)(SUBSTRING([Column 11],1,2) + ":" + SUBSTRING([Column 11],3,2) + ":" + SUBSTRING([Column 11],5,2)) 

but still its not working.

Can anyone help on this?

Answer 1

The error that you posted in the question is a bit misleading.

The actual error produced in SSDT is :

The data types "DT_WSTR" and "DT_DBTIME" are incompatible for the conditional operator. The operand types cannot be implicitly cast into compatible types for the conditional operation. To perform this operation, one or both operands need to be explicitly cast with a cast operator.

and ofcourse the one you posted at the end:

Error at Data Flow Task [Derived Column [18]]: Computing the expression "(ISNULL([Column 0]) ? "000000" : (DT_DBTIME) (SUBSTRING([Column 0],1,2) + ":" + SUBSTRING([Column 0],3,2) + ":" + SUBSTRING([Column 0],5,2)))" failed with error code 0xC00470A0. The expression may have errors, such as divide by zero, that cannot be detected at parse time, or there may be an out-of-memory error.

In your case this simply means that you cannot define (DT_DBTIME) to one part of the conditional operation,

Else Part

: (DT_DBTIME)(SUBSTRING([Column 11],1,2) + ":" + SUBSTRING([Column 11],3,2) + ":" + SUBSTRING([Column 11],5,2))

leaving the other part as "DT_WSTR"

IF Part

ISNULL ( [Column 11] ) ? "000000"

So the correct Transformation rule should be:

(DT_DBTIME)(IS( [Column 11] ) ? "000000" : (SUBSTRING([Column 11],1,2) + ":" + SUBSTRING([Column 11],3,2) + ":" + SUBSTRING([Column 11],5,2)))