mysql常用sql语句

1.判断数据库中表是否存在

string strsql = "select count(1) from INFORMATION_SCHEMA.TABLES where TABLE_SCHEMA='hfslog' and TABLE_NAME='" + TableName + "'";

例如：

select count(1) from INFORMATION_SCHEMA.TABLES where TABLE_SCHEMA='hfslog' and TABLE_NAME='datflow20170812';

2.判断表中字段是否存在

string sql = "select count(*) from information_schema.columns where table_name = '"+tableName+"' and column_name = '"+columnName+"'";

例如：

select count(*) from information_schema.columns where table_name = 'datflow20170810' and column_name = 'id'

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