CQL (Common Query Language) is a plain text query language created by the OGC for the Catalogue Web Services specification.

It is a human-readable query language, and its syntax is very similar to SQL syntax, but with extremely limited functionality. For example, it can’t encode ID filters, and it requires an attribute to be on the left side of any comparison operator.

Because of the mentioned limitations, GeoServer provides an extended version of CQL, called ECQL.

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