Question

我需要将一个参数传递给存储过程以获取列数据类型为Bit的所有行。例如：

select * from user where active = true   // get all actived users 
select * from user where active = false   // get all Not actived users

当我需要获取所有行时，我该怎么办？我将活动值作为参数传递给C＃

Answer 1

您可以将active参数设为可选参数，并执行以下操作：

ALTER PROCEDURE [dbo].[GetUsers](
    @Active BIT = NULL
) AS

BEGIN

    SELECT * 
    FROM user
    WHERE (@Active IS NULL OR active = @Active)

END

在代码中，添加一个重载的获取方法：

var users = GetUsers(true); //pass active as true

var users = GetUsers(); //dont pass active parameter, return all users

Answer 2

取决于活动列中的数据。如果你有真假，我怀疑，因为sql db不支持这些值tyes，但你至少可以有位值类型。所以位只能有1或0（一或零）。

Answer 3

使用?取消您的C＃bool值：

bool? showActive = SomeCode();

传递可能为空的showActive标志，并使用以下命令更新SQL代码：

select * from user where active = @showActive or @showActive is null

如果传递的@showActive参数为null，则返回所有行。

Answer 4

这也可以像：

那样实现

WHERE user.active = ISNULL(@Active, user.active)

使用它，SQL服务器可以使用索引（如果有索引可以使用）。

Answer 5

我喜欢这样的事情。给定存储过程：

create procedure dbo.SelectAccounts

  @fExpired bit

as

  set ansi_nulls              on
  set concat_null_yields_null on

  select *
  from dbo.Account acct
  where acct.Expired = @fExpired = coalesce( @fExpired , acct.Expired )
  -- a more verbose alternative test
  --    (          acct.Expired =  @fExpired
  --      OR (     acct.Expired is null
  --           and @fExpired    is not null
  --         )
  --    )

  return 0 

go

我生成一个看起来像这样的类：

public class dbo_SelectAccounts
{
  public const string STORED_PROCEDURE_NAME = @"dbo.SelectAccounts";

  private string   ConnectString    { get ;         set ; }
  public int       ReturnCode       { get ; private set ; }
  public int       TimeoutInSeconds { get ; private set ; }
  public DataTable ResultSet        { get ; private set ; }
  public int       RowCount         { get { return this.ResultSet.Rows.Count ; } }

  public int Exec( bool? @fExpired )
  {
    using ( SqlConnection  conn = new SqlConnection( this.ConnectString ) )
    using ( SqlCommand     cmd  = conn.CreateCommand() )
    using ( SqlDataAdapter sda  = new SqlDataAdapter(cmd) )
    {

      cmd.CommandText    = STORED_PROCEDURE_NAME;
      cmd.CommandType    = CommandType.StoredProcedure;
      cmd.CommandTimeout = this.TimeoutInSeconds ;

      // 1. Format parameter to stored procedure
      SqlParameter p1 = new SqlParameter( @"@fExpired" , SqlDbType.Bit ) ;
      if ( @fExpired == null )
      {
        p1.Value = System.DBNull.Value ;
      }
      else
      {
        p1.Value = @fExpired ;
      }
      cmd.Parameters.Add( p1 );

      // add return code parameter
      SqlParameter pReturnCode = new SqlParameter();
      pReturnCode.SqlDbType    = System.Data.SqlDbType.Int;
      pReturnCode.Direction    = System.Data.ParameterDirection.ReturnValue;
      cmd.Parameters.Add( pReturnCode );

      conn.Open();
      sda.Fill( this.ResultSet ) ;
      conn.Close();

      this.ReturnCode = (int)pReturnCode.Value;

    }

    return this.ReturnCode;
  }

  #region constructors

  public dbo_SelectAccounts( string connectionString , int executionTimeoutInSeconds )
  {
    this.ConnectString    = connectionString          ;
    this.TimeoutInSeconds = executionTimeoutInSeconds ;
    this.ReturnCode       = -1                        ;
    this.ResultSet        = new DataTable()           ;
    return ;
  }

  public dbo_SelectAccounts( string connectionString )
  : this( connectionString , 30 )
  {
    this.ConnectString = connectionString;
  }

  public dbo_SelectAccounts( SqlConnectionStringBuilder csb , int executionTimeoutInSeconds )
  : this( csb.ConnectionString , executionTimeoutInSeconds )
  {
    return;
  }

  public dbo_SelectAccounts( SqlConnectionStringBuilder csb )
  : this( csb.ConnectionString )
  {
    return;
  }

  #endregion constructors

}

用法很简单：

dbo_SelectAccount sp = new dbo_SelectAccounts( myConnectString ) ;
int               rc = sp.Exec( null ) ;

获取数据类型为bit的所有列行

5 个答案: