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Input data columns (DataStage)

Input data columns (DataStage)

The single column specified for evaluation can be of any data type. If you compare columns they must be of the same or compatible data types. Column data type conversion is based on the rules mentioned in this section.

If you specify a single column for evaluation, that column can be of any data type. Note that IBM® DataStage®’s treatment of strings differs slightly from that of standard SQL. If you compare columns they must be of the same or compatible data types. Otherwise, the operation terminates with an error. Compatible data types are those that IBM DataStage converts by default. Regardless of any conversions the whole row is transferred unchanged to the output. If the columns are not compatible upstream of the filter stage, you can convert the types by using a Modify stage prior to the Filter stage.

Column data type conversion is based on the following rules:

  • Any integer, signed or unsigned, when compared to a floating-point type, is converted to floating-point.
  • Comparisons within a general type convert the smaller to the larger size (sfloat to dfloat, uint8 to uint16, and so on.)
  • When signed and unsigned integers are compared, unsigned are converted to signed.
  • Decimal, raw, string, time, date, and timestamp do not figure in type conversions. When any of these is compared to another type, filter returns an error and terminates.

The input field can contain nulls. If it does, null values are less than all non-null values, unless you specify the operator’s nulls last option.

Note: The conversion of numeric data types might result in a loss of range and cause incorrect results. IBM DataStage displays a warning message to that effect when range is lost.
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