我的CREATE TABLE MySQL语法有什么问题？

Question

I am having some trouble with the CREATE IF NOT EXISTS clause.

I am using a C# application to create a MySQL table, the connection to DB has been established so it's not a problem.

The error I am getting is an exception when I try to execute the query, I get the message:

MySql.Data.MySqlClient.MySqlException (0x80004005): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF NOT EXISTS(price VARCHAR, time VARCHAR)' at line 1

In debug mode, the immediate window shows my command string as:

CREATE TABLE ticks_14_11_2016 IF NOT EXISTS(price VARCHAR, time VARCHAR)

From the examples I have seen, this should be the proper syntax. I am not worried about constraints and keys for the time being, I just need the query to execute...

Also, here is the C# code which I use to build the string and execute query:

string tableName = "ticks_" + getTodayString();
            if (databaseClient.IsConnect()) {
                string tableString = "CREATE TABLE " + tableName +
                " IF NOT EXISTS" +
                "(price VARCHAR, " +
                "time VARCHAR)";

                try
                {
                    var command = databaseClient.Connection.CreateCommand();
                    command.CommandText = tableString;
                    command.ExecuteNonQuery();
                } catch (Exception e)
                {
                    Console.WriteLine(e);
                }
            }

The variable databaseClient has a member that is the MySQLConnection object

Also, my server version is: 5.6.28-76.1

Answer 1

You have the if not exists in the wrong place, and also, the varchar type needs a mandatory length argument.

A corrected version should be:

CREATE TABLE IF NOT EXISTS ticks_XXXXX (price VARCHAR(10), time VARCHAR(10));

Change the length to whatever is appropriate for you.

For more information see the reference manual .

Answer 2

You have other ways also to check whether table exists in database or not.

IF OBJECT_ID(N'dbo.ticks_14_11_2016', N'U') IS NOT NULL
BEGIN
    ------Exists
END

IF EXISTS(SELECT 1 FROM sys.Objects WHERE  Object_id = 

OBJECT_ID(N'dbo.ticks_14_11_2016') AND Type = N'U')
BEGIN
   ------Exists
END

    IF EXISTS(SELECT 1 FROM sys.Tables WHERE  Name = N'ticks_14_11_2016 ' AND Type = N'U')
 BEGIN
      ----Exists
 END

IF OBJECT_ID('ticks_14_11_2016') IS NOT NULL
BEGIN
     -----Exists
END

Use your logic accordingly