For example, you can create an expression that specifies all parcels whose area is larger than 4000 square feet. A query containing this expression displays or selects only parcels that meet those criteria.
Use expressions to filter geospatial data, select a subset of data, calculate values, or convert data from one data type to another. Use text expressions to format text strings for display, for example, as labels. Use numeric expressions to apply math functions to properties with numeric values.
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|Ways to Use Expressions||Description|
You can filter or select data based on the value of one or more properties.
A simple expression evaluates a single property, but you can create complex expressions that use multiple properties or multiple values. For example, you could create an expression that shows counties with a population over 50,000 but under 100,000.
The result of a filter expression must be a Boolean value.
You can calculate a new value based on existing values. For example, you can do the following:
Conversions change data values from one data type to another. For example, if a data store keeps date values as text, you can convert these values to date strings. Then you can useon them.
You can also convert numeric or text strings to a particular numeric format, for example to a single- or double-precision number. You can convert numeric values into text strings, for example, to extract a substring or find the number of characters in the string.
With text expressions, you can analyze and manipulate strings. For example, you can do the following:
Numeric expressions operate only on numeric values. They use math functions, with which you can analyze and manipulate numeric strings. For example, with numeric expressions, you can do the following:
With filters, you can work with a subset of your data. For example, if your map includes all the counties in California, you can create a filter to show only counties with a population over 50,000.
Use expressions to do the following:
Use aor a to determine the content of labels when you style your map.
Use expressions in AutoCAD Map 3D to determine how property values are specified after merging or splitting features.