Tip – Always state CONCATENATE or NOCATENATE

 

Every LOAD statement should state its intention to concatenate or not via the CONCATENATE and NOCATENATE keywords unless assumed concatenation is the intended course of action in which case a /* comment */ should be placed near LOAD to remind the developer.

QVW assumes that you want to concatenate if the new table being loaded has identical field names to a currently loaded table. (The field sequence or contents doesn’t matter, only the names, including capitalization of those names). This can be what you intended but often it is not. QVW will not warn, log or otherwise indicate that it has assumed you want to concatenate and that can be an issue when you didn’t intend concatenation to happen.

Naming the new table in the LOAD statement does not prevent concatenation either.

Problem1:

Table1:

LOAD

field1

<etc>

;

Table2:

LOAD

field1

<etc>

;

 

Table1 will exist but Table2 wont. Table1’s contents are automatically concatenated with the contents of the LOAD statement for Table2. Table2 itself is never created as a separate table.

Solution:

Table1:

NOCONCATENATE

LOAD

field1

<etc>

;

Table2:

NOCONCATENATE

LOAD

field1

<etc>

;

 

Both Table1 and Table2 will exist.

 

See Tip – “Detecting QVW’s automatic renaming of tables” with a procedure that will help your code be more aware that QVW did something unexpected.