c# - ExecuteStoreQuery 和 ExecuteStoreCommand 有什么区别

Question

在 entityframework 中，我们可以使用 ExecuteStoreQuery 或 ExecuteStoreCommand 来执行 sql 查询。那么它们之间有什么区别（不同的场景）？

谢谢你。

Answer 1

从MSDN可以看出区别

执行存储查询

直接针对返回一系列类型化结果的数据源执行查询。

和MSDN

执行存储命令

使用现有连接直接对数据源执行任意命令。

ExecuteStoreQuery 示例：

using (SchoolEntities context =
    new SchoolEntities())
{
    // The following three queries demonstrate 
    // three different ways of passing a parameter.
    // The queries return a string result type.

    // Use the parameter substitution pattern.
    foreach (string name in context.ExecuteStoreQuery<string>
        ("Select Name from Department where DepartmentID < {0}", 5))
    {
        Console.WriteLine(name);
    }

    // Use parameter syntax with object values.
    foreach (string name in context.ExecuteStoreQuery<string>
        ("Select Name from Department where DepartmentID < @p0", 5))
    {
        Console.WriteLine(name);
    }
    // Use an explicit SqlParameter.
    foreach (string name in context.ExecuteStoreQuery<string>
        ("Select Name from Department where DepartmentID < @p0",
            new SqlParameter { ParameterName = "p0", Value = 5 }))
    {
        Console.WriteLine(name);
    }
}

ExecuteStoreCommand 示例

public class DepartmentInfo
{
    private DateTime _startDate;
    private String _name;
    private Int32 _departmentID;

    public Int32 DepartmentID
    {
        get
        {
            return _departmentID;
        }
        set
        {
            _departmentID = value;
        }
    }
    public String Name
    {
        get
        {
            return _name;
        }
        set
        {
            _name = value;
        }
    }
    public DateTime StartDate
    {
        get
        {
            return _startDate;
        }
        set
        {
            _startDate = value;
        }
    }
}

public static void ExecuteStoreCommands()
{
    using (SchoolEntities context =
        new SchoolEntities())
    {

        int DepartmentID = 21;
        // Insert the row in the Department table. Use the parameter substitution pattern.
        int rowsAffected = context.ExecuteStoreCommand("insert Department values ({0}, {1}, {2}, {3}, {4})",
                        DepartmentID, "Engineering", 350000.00, "2009-09-01", 2);
        Console.WriteLine("Number of affected rows: {0}", rowsAffected);

        // Get the DepartmentTest object. 
        DepartmentInfo department = context.ExecuteStoreQuery<DepartmentInfo>
            ("select * from Department where DepartmentID= {0}", DepartmentID).FirstOrDefault();

        Console.WriteLine("ID: {0}, Name: {1} ", department.DepartmentID, department.Name);

        rowsAffected = context.ExecuteStoreCommand("delete from Department where DepartmentID = {0}", DepartmentID);
        Console.WriteLine("Number of affected rows: {0}", rowsAffected);
    }
}