selectcount(1)frominformation_schema.columnswheretable_schema="testdatabase"andtable_name='testtable' //查看某个数据库中某个表有多少字段 selectcount(1)frominformation_schema.columnswheretable_schema="testdatabase" //查看某个数据库中整体有多少字段 selectcount(1),table_schemafrominformation_schema.tableswheretable_schema='test...