在多个ODBC数据库中执行相同的SQL查询

Question

How to execute the same SQL query across multiple ODBC databases., like MySQL, Oracle and SQL Server.

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Data;
  namespace DataAccessLayer
  public DataSet GetSourceTables()
    {
        string query = "Select DISTINCT(name) FROM sys.Tables";
        DataSet ds = new DBHelper().ExecuteDataSet(query);
        return ds;
    }

My objective is to do select all tables name from different DSN, like MySQL, Oracle etc.

Answer 1

In general you can use the same SQL query in various databases only if it is simple query. There are differences when you need to use date, datetime, string functions etc.

From your query I see that you want to get table names (part of database schema). Such query is vendor specific. Each vendor saves schema info in different tables, so for PostgreSQL you will have to look at information_schema.columns , for Oracle there is user_tab_columns and Informix use systables . You can create queries for each database and then try them one by one until one succeeds. But most DB drivers has procedures/methods to discover DB schema. In Java there is DatabaseMetaData.getTables() , in ODBC you can use SQLTables() . For C# look at: Retrieving table schema information using C#