Python提取出SQL语句中where的值

一、需求解析

例如有SQL=“select * from t1 where name='DriverWon';”，需要提取出where的值name=‘DriverWon’

当然也存在其他的情况，将可能出现的SQL语句列举如下：

sql_list = ["select * from t1 where name='DriverWon';",
            "select * from t1 where name='DriverWon' order by 1 desc;",
            "select * from t1 where name='DriverWon' limit 10;",
            "select * from t1 where name='DriverWon' or id=10;",
            "select * from t1 where name='DriverWon' AND id>10 and is_del is not null order by 1 desc;",
            "select * from t1 where name='DriverWon' ;",
            "select * from t1;",
            "select * from t1 where id =(select id from t2 where name='DriverWon');"]

二、代码实现

sqlparse解析器提取

使用sqlparse库解析SQL，提取出where的值

import sqlparse


def where_extract_sqlparse(sql):
    """
    SQL解析器（sqlparse）提取SQL中where的值
    :param sql:
    :return:
    """
    stmt = sqlparse.parse(sql)[0].tokens
    where_list = [s.value for s in stmt if isinstance(s, sqlparse.sql.Where)]
    return where_list


if __name__ == "__main__":
    for i, v in enumerate(sql_list):
        print(f"SQL{i + 1}提取结果：{where_extract_sqlparse(v)}")

运行结果：

re正则表达式提取

使用re库匹配并提取出where的值

import re


def where_extract_re(sql):
    """
    正则表达式提取SQL中where的值
    :param sql:
    :return:
    """
    # 提取where和关键字之间的字符串
    match = re.search(r'where\s+([^;]*?(?=order by|limit|;|$))', sql, re.IGNORECASE)  # re正则表达式匹配，忽略大小写
    if not match:
        result = ''
    else:
        result = match.groups(1)[0]
    # 根据and或or拆分结果
    if 'and' in result.lower():
        result = result.replace('AND', 'and')
        result = [s.strip() for s in result.split('and')]
    elif 'or' in result.lower():
        result = result.replace('OR', 'or')
        result = [s.strip() for s in result.split('or')]
    return result


if __name__ == "__main__":
    for i, v in enumerate(sql_list):
        print(f"SQL{i + 1}提取结果：{where_extract_re(v)}")

运行结果：

三、结果分析

从运行结果来看，使用re方法更加适合于前文描述的需求，但是当遇到更为复杂的SQL时（多重嵌套的子查询等）结果可能不尽人意，若是使用sqlparse方法则需要再次处理提取出的结果，将where、空格以及分号等字符去除。