Changing the order of columns in an output dataset requires the use of a compile-time-only statement appearing before the SET statement to order the columns in the Program Data Vector during compilation.
Unfortunately, not all compile-time-only statements will allow you to do this easily.
The dataset SASHELP.CLASS hass the variables: NAME. SEX, AGE, HEIGHT and WEIGHT in that order.
The best-known hack for ordering columns is the RETAIN statement: all variables read from a dataset are retained automatically anyway, so this is a no-harm no-foul approach.
If only some of the variables are listed on the RETAIN statement, their order will be as listed, the remaining variables will appear in their original order:
data ordersome ; retain age weight ; set sashelp.class ; run ;
gives columns: AGE, WEIGHT, NAME, SEX, HEIGHT
To re-order all columns they must all be listed. The FORMAT statement can be used in the same way as the RETAIN statement:
data orderall ; format age weight height sex name ; set sashelp.class ; run ;
The FORMAT statement does not give a syntax error if a format is not specified. The ATTRIB and LENGTH statements however produce a syntax error if used in the same way:
data attributes ; attrib age weight height ; set sashelp.class ; run ; data lengths ; length age weight ; set sashelp.class ; run ;
The KEEP statement (along with the DROP statement) is also a compile-time-only statement, but although it will control which columns appear in the output dataset it cannot be used to control their order. The code:
data keepsome ; keep weight age sex ; set sashelp.class ; run ;
still leaves the columns in the order SEX, AGE, WEIGHT.Tags: compile-time, format, order, retain