是否可以在sqlite中创建javascript用户定义函数 [英] Is it possible to create a javascript User-defined function in sqlite

问题描述

背景:

• Firefox 3包括 SQLite 版本3.5.9.Firefox还允许使用javascript和可以调用嵌入式SQLite引擎.

• Firefox 3 includes SQLite version 3.5.9. Firefox also allows extensions, which are written in javascript and can call the embedded SQLite engine.

按预期执行以下命令SQL语句'SELECT"TEXT" REGEXP"T *";'给出一个错误，因为有SQLite本身不包含REGEXP函数.

As expected, executing the following SQL statement 'SELECT "TEXT" REGEXP "T*";' gives an error, since there is no REGEXP function natively included in SQLite.

javascript包含一个内置的regexp函数.

javascript includes a built in regexp function.

SQLite允许通过SELECT load_extension('filename');

SQLite allows loadable extensions via SELECT load_extension('filename');

问题:是否可以在SQLite中加载用javascript编写的可以执行REGEXP的扩展程序?

推荐答案

是.可以调用javascript函数

Yes. It is possible to call javascript functions

//(thanks to Mirnal Kant, SQLManager)
//Version 2 -- Prevent Firefox crashing 
//          -- Suspect a problem with continual creation of Regex objects

var g_RegExpString = null;
var g_RegExp = null;

//functions to be created for the db
var smDbFunctions = { 
  // (0) = Regex Expression
  // (1) = Column value to test
    regexp: {
        onFunctionCall: function(val) {
            if (g_RegExp == null || val.getString(0) != g_RegExpString) 
            {
                g_RegExpString = val.getString(0);
                g_RegExp = new RegExp(g_RegExpString);
            }
            if (val.getString(1).match(g_RegExp)) return 1;
            else return 0;
        }
    }
}; 

实例化一个SQLite实例后:

after instantiating a SQLite instance:

Database.createFunction("REGEXP", 2, smDbFunctions.regexp);

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