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SQL Extension | SQL 语法拓展,目标是打造 "易读易写 方便维护" 的 sql 脚本

Project description

sqlx

SQL Extension

一种扩展 sql 的语言,目标是打造 "易读易写 方便维护" 的 sql 脚本

使用方法

Windows 系统,直接下载 sqlx.exe 放置于 .sqlx 脚本文件 同目录下

双击 sqlx.exe 即可完成自动编译,在 dist 目录中生成 sql 文件

语法简介

1. 通过 define 定义变量,可在脚本中反复引用

示例:

define field_name age

SELECT {field_name} from students WHERE {field_name} > 10;
SELECT {field_name} from teachers WHERE {field_name} > 10;

编译生成 sql 为:

SELECT age from students WHERE age > 10;
SELECT age from teachers WHERE age > 10;

2. 通过 block 定义脚本片段,并反复引用

示例:

-- ! 定义片段
block good_students(score)
    (
        SELECT
            *
        FROM
            students
        WHERE
            score > {score}
    ) AS good_students
endblock

SELECT name FROM {good_students(80)};
SELECT count(*) FROM {good_students(80)};

编译生成 sql 为:

SELECT name FROM 
    (
        SELECT
            *
        FROM
            students
        WHERE
            score > 80
    ) AS good_students
;
SELECT count(*) FROM 
    (
        SELECT
            *
        FROM
            students
        WHERE
            score > 80
    ) AS good_students
;

3. 循环

通过 for 批量循环生成脚本(暂不支持循环嵌套)

示例1:

{% for n in table1,table2,table3 %}
    SELECT * FROM {n};
{% endfor %}

编译生成 sql 为:

SELECT * FROM table1;
SELECT * FROM table2;
SELECT * FROM table3;

示例2:

{% for n|m in table1|id,table2|name,table3|age %}
    SELECT {m} FROM {n};
{% endfor %}

编译生成 sql 为:

SELECT id FROM table1;
SELECT name FROM table2;
SELECT age FROM table3;

4. 判断

通过 if 生成逻辑分支脚本(暂不支持 if 嵌套)

示例1:

define a 8

{% if {a} > 4 %}
    SELECT * FROM table1;
{% endif %}

编译生成 sql 为:

SELECT * FROM table1;

示例2:

{% for n in table1,table2,table3 %}
    {% if n == table1 %}
        SELECT id, name FROM {n};
    {% else%}
        SELECT * FROM {n};
    {% endif %}
{% endfor %}

编译生成 sql 为:

SELECT id, name FROM table1;
SELECT * FROM table2;
SELECT * FROM table3;

更多示例可参考 demo.sqlx

在 Python3 程序中使用 sqlx 模块

如果使用 Python,这里还特别为你提供了 sqlx 的 python 模块包

可以方便地跨平台安装,以及更加灵活地处理和编译脚本

安装

pip install sqlx

使用 sqlx.build 编译脚本

import sqlx

my_script = """
{% for n in table1,table2,table3 %}
    {% if n == table1 %}
        SELECT id, name FROM {n};
    {% else%}
        SELECT * FROM {n};
    {% endif %}
{% endfor %}
"""

sql = sqlx.build(my_script, pretty=True)
print(sql)

使用 sqlx 命令行工具

  1. 直接执行 sqlx 命令,可一键编译当前目录下的所有脚本
$ ls
test1.sqlx    test2.sqlx

$ sqlx
dist/test1.sql built
dist/test2.sql built
Finish!

$ ls dist
test1.sql    test2.sql
  1. sqlx 命令后跟随目录路径参数,可编译指定路径下的所有脚本
$ ls test
test3.sqlx    test4.sqlx

$ sqlx ./test/
test/dist/test3.sql built
test/dist/test4.sql built
Finish!

$ ls test/dist
test3.sql    test4.sql
  1. sqlx 命令后跟随文件路径参数,可编译指定的单个脚本
$ sqlx ./test/test3.sqlx
test/dist/test3.sql built
Finish!

$ ls test/dist
test3.sql

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