数据库相关SQL

一般来说各个数据库的sql都是一样的语法，但还是说明一下这里的是postgres数据库。

下列示例中，
param_maintain是table，
type, param, param_value, unit, start_use_time, maintain_time是列名。

查询
SELECT type, param, param_value, unit, start_use_time, maintain_time
FROM public.param_maintain;
删除
delete from param_maintain where param = ‘35’ ;
插入
INSERT INTO param_maintain (type, param, param_value, unit, start_use_time, maintain_time) VALUES
(‘04’, ‘35’, 0.4, ‘um’, ‘2023-09-27’, ‘2024-01-04’)， (‘04’, ‘35’, 0.4, ‘um’, ‘2023-09-27’, ‘2024-01-04’)
更新
UPDATE table_name
SET column1 = value1, column2 = value2…, columnN = valueN
WHERE [condition];
eg:
update param_maintain set param_value = 0.4
where type = ‘4’ and param = ‘35’

示例代码

def get_conn_pg():f = open(r'./config.yaml', encoding='utf-8')config_param = yaml.load(f.read(), Loader=yaml.FullLoader).get('postpsql')conn = psycopg2.connect(host=config_param.get('host'),port=config_param.get('port'),user=config_param.get('user'),password=config_param.get('password'),database=config_param.get('database'))cur = conn.cursor()return conn, curdef close_conn_pg(cur, conn):cur.close()conn.close()conn, cur = get_conn_pg()
table = 'param_maintain'
sql_select = f""" select * from "{table}" where type = '04' """
cur.execute(sql_select)
# conn.commit()
data_list = cur.fetchall()
fields = [desc[0] for desc in cur.description]
close_conn_pg(cur, conn)df_db_params = pd.DataFrame(data_list)
df_db_params.columns = fields