常用sql语句（mysql）

#给表新增列
sql = '''
alter table table_name
add column col_name varchar(255)
not null default default_value
'''

#增加表列，指定格式
sql = '''
alter table table_name
add col_name boolean
'''

#将指定列移到第一列
sql = '''
alter table table_name
modify col_name varchar(255) first
'''

#将指定列移动到某一列后面
sql = '''
alter table table_name
modify col_name varchar(255) after col_name2
'''

#与另一表关联进行插入数据
sql = '''
update table_name1 t1, table_name2 t2
set t1.area = t2.oc
where condition1=condition2
'''

#更改表名
sql = '''
alter table table_name rename table_name2
'''

#表去重查询
sql = '''
select distinct(*) from table_name
'''

#改变表中列名（必须同时指定格式）
sql = '''
alter table table_name
change col1 col2 varchar(255)
'''

#将表2中的数据插入到表1中
sql = '''
insert into table_name
select * from table_name2
'''

#删除指定表中的主键
sql = '''
alter table table_name
drop primary key
'''

sql = '''
alter table table_name
add primary key(col_name)
'''

#删除表中指定列
sql = '''
alter table table_name
drop col_name
'''

#删除表中指定行
sql = '''
delete from table_name where col_name=value
'''

#删除指定列的默认值
sql = '''
alter table table_name alter column col_name drop default
'''

#设置指定列的默认值（若改变原有默认值，则先执行删除默认，再设置默认）
sql = '''
alter table table_name alter column col_name set default default_value
'''