Question

我想在点击按钮后在我的数据库中创建表。在Button_Click函数中，我有一个代码

SqlConnection conn = new SqlConnection(@"MyConnectionString");

conn.Open();

SqlCommand cmd = new SqlCommand("CREATE TABLE '" + tableName+ "' (IdPy INT IDENTITY(1,1), Question NVARCHAR (MAX) NOT NULL, IsChecked BIT NOT NULL,  CONSTRAINTPK_'" + tableName+ "' PRIMARY KEY(Id) )", conn);

cmd.ExecuteNonQuery();
conn.Close();

tableName是我的String变量（其值2018-04-18 asd - 是的，我希望该表具有这样的名称）。单击按钮后出现错误：

System.Data.SqlClient.SqlException：＆＃39; 2018-04-18 asd＆＃39;附近的语法不正确。＆＃39;

我认为问题出在我的SqlCommand中。如果你能帮助我解决这个问题，我将不胜感激。

Answer 1

tableName变量似乎是2018-04-18 asd。如果这确实是正确的表名，则需要将其（和约束）转义为方括号：

SqlCommand cmd = new SqlCommand("CREATE TABLE [" + tableName + "] (IdPy INT IDENTITY(1,1), Question NVARCHAR (MAX) NOT NULL, IsChecked BIT NOT NULL, CONSTRAINT [CONSTRAINTPK_" + tableName+ "] PRIMARY KEY(Id) )", conn);

Answer 2

您应该转义（如果是MS SQL，则为[...] table 和约束名称：

  //DONE: wrap IDisposable into using
  using(SqlConnection conn = new SqlConnection(@"MyConnectionString")) {
    conn.Open();

    //DONE: Make sql readable. Can you see that you've skipped CONSTRAINT keyword?
    string sql = 
      $@"CREATE TABLE [{tableName}] (
           -- Fields
           IdPy      INT IDENTITY(1,1),
           Question  NVARCHAR (MAX)     NOT NULL, 
           IsChecked BIT                NOT NULL,

           -- Constraints
           --DONE: Constraint key word (optional in some RDBMS) added 
           CONSTRAINT [CONSTRAINTPK_{tableName}] PRIMARY KEY(Id) 
         )";

    //DONE: wrap IDisposable into using
    using (qlCommand cmd = new SqlCommand(sql, conn)) {
      cmd.ExecuteNonQuery();
    }
  }

Answer 3

通过使用字符串变量和参数化字符串格式来识别SQLCommand的问题可能更容易。一个例子：

string query = "CREATE TABLE @tablename (IdPy INT IDENTITY(1,1), 
Question NVARCHAR (MAX) NOT NULL, IsChecked BIT NOT NULL,  
CONSTRAINTPK_@tablename PRIMARY KEY(Id) )";

string param = new {@tablename = txttable.txt(example)};

SqlCommand cmd = new SqlCommand(query, param, conn);

这可能有助于逐步确保您需要检查的变量更简洁。

SQLCommand，创建表

3 个答案: