126 lines
2.4 KiB
Markdown
126 lines
2.4 KiB
Markdown
# SQL参数
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## #{} 注入参数
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作用和`mybatis`一致，都是将`#{}`区域替换为占位符`?`
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```javascript
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var id = 123;
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return db.select("""
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select * from sys_user where id = #{id}
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""");
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// 运行时生成的SQL为：select * from sys_user where id = ?
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```
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此方法可以避免`sql`注入。
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## ${} 拼接参数
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作用和`mybatis`一致，都是将`${}`区域替换为对应的字符串
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```javascript
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var id = 123;
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return db.select("""
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select * from sys_user where id = ${id}
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""");
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// 运行时生成的SQL为：select * from sys_user where id = 123
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```
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## 动态SQL参数
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通过`?{condition,expression}`来实现动态拼接`SQL`
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```javascript
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return db.select("select * from sys_user ?{id,where id = #{id}}");
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// 当id有值时,生成SQL：select * from sys_user where id = ?
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// 当id无值时,生成SQL：select * from sys_user
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return db.select("select * from sys_user ?{id!=null&&id.length() > 3,where id = #{id}}");
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```
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## 循环拼接参数
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两种办法：
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### in语法自动展开
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```javascript
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var ids = [1,2,3,4,5,6];
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//会自动变成select * from sys_user where id in(?,?,?,?,?,?)
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return db.select('select * from sys_user where id in(#{ids})');
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```
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### 循环拼接SQL
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```javascript
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var list = [1,2,3,4,5];
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var sql = "select * from sys_user where ";
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for(index,item in list){
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sql = sql + 'id = #{list['+index+']}';
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if(index + 1 < list.size()){
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sql = sql + ' or ';
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}
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}
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return db.select(sql);
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```
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## Mybatis语法支持
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### 支持的关键字
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- `<if>`
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- `<elseif>`
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- `<else>`
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- `<where>`
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- `<foreach>`
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- `<trim>`
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- `<set>`
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### if
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```javascript
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var sql = """
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select * from test_data
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where 1 = 1
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<if test="id != null">
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and id = #{id}
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</if>
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"""
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return db.select(sql)
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```
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### where
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```javascript
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var sql = """
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select * from test_data
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<where>
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<if test="id != null">
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and id = #{id}
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</if>
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</where>
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"""
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return db.select(sql)
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```
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### set、trim
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```javascript
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var sql = """
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update test_data
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<set>
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<if test="name != null">
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name = #{name}
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</if>
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<if test="content != null">
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content = #{content}
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</if>
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</set>
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where `id` = #{id}
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"""
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return db.update(sql)
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```
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### foreach
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```javascript
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var sql = """
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select * from test_data
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where id in
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<foreach item='item' index='index' collection='body.ids'
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open="(" separator="," close=")">
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#{item}
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</foreach>
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"""
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return db.select(sql)
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```
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