CQL and ECQL

最新推荐文章于 2025-06-10 09:05:24 发布

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最新推荐文章于 2025-06-10 09:05:24 发布

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分类专栏： WebGIS 地理信息系统文章标签： webgis

本文链接：https://blog.youkuaiyun.com/bpwangxch/article/details/88534407

本文介绍了GeoServer中用于WMS和WFS请求的CQL和ECQL查询语言，包括它们的用途、语法示例以及在动态渲染图层中的应用。CQL是一种更易读的查询语言，而ECQL则扩展了CQL的功能，提供更灵活的查询选项。通过一系列示例，展示了如何使用这些语言进行属性和几何过滤，如范围查询、文本匹配、算术表达式以及几何过滤等。

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本文讲述了如何使用CQL and ECQL查询语言，文章摘自GeoServer官网。在GeoServer的WMS和WFS动态渲染图层，并通过不同的例子具体说明。其中CQL and ECQL查询语言放置在定义WMS和WFS图层的params中，示例代码如下：

var WMSsource = new ol.source.ImageWMS({
    ratio: 1,
    url: 'http://wangxch:8081/geoserver/QHH/wms',
    params: {
        'FORMAT': format,
        'VERSION': '1.1.1',
        "LAYERS": 'QHH:p242landownershipP',
        "exceptions": 'application/vnd.ogc.se_inimage',
        'CQL_FILTER': "province=xining" //过滤条件
    }
});

CQL (Common Query Language) is a query language created by the OGC for the Catalogue Web Services specification. Unlike the XML-based Filter Encoding language, CQL is written using a familiar text-based syntax. It is thus more readable and better-suited for manual authoring.

However, CQL has some limitations. For example it cannot encode id filters, and it requires an attribute to be on the left side of any comparison operator. For this reason, GeoServer provides an extended version of CQL called ECQL. ECQL removes the limitations of CQL, providing a more flexible language with stronger similarities with SQL.

GeoServer supports the use of both CQL and ECQL in WMS and WFS requests, as well as in GeoServer’s SLD dynamic symbolizers. Whenever the documentation refers to CQL, ECQL syntax can be used as well (and if not, please report that as a bug!).

This tutorial introduces the CQL/ECQL language by example. For a full reference, refer to the ECQL Reference.

Getting started

The following examples use the topp:states sample layer shipped with GeoServer. They demonstrate how CQL filters work by using the WMS