SqlConnection.GetSchema 方法

定義

命名空間:

Microsoft.Data.SqlClient

組件:

Microsoft.Data.SqlClient.dll

套件:

Microsoft.Data.SqlClient v7.1.0

多載

名稱	Description
GetSchema()	回傳此 SqlConnection資料來源的結構資訊。 欲了解更多關於結構的資訊，請參閱 SQL Server 架構集合。
GetSchema(String)	會使用指定的字串作為結構名稱，回傳該 SqlConnection 資料庫的結構資訊。
GetSchema(String, String[])	回傳此 SqlConnection 資料來源的結構資訊，並使用指定的字串作為結構名稱，並以指定的字串陣列作為限制值。

GetSchema()

回傳此 SqlConnection資料來源的結構資訊。 欲了解更多關於結構的資訊，請參閱 SQL Server 架構集合。

public:
 override System::Data::DataTable ^ GetSchema();

public override System.Data.DataTable GetSchema();

abstract member GetSchema : unit -> System.Data.DataTable
override this.GetSchema : unit -> System.Data.DataTable

Public Overrides Function GetSchema () As DataTable

傳回

DataTable

DataTable A 包含結構資訊。

GetSchema(String)

會使用指定的字串作為結構名稱，回傳該 SqlConnection 資料庫的結構資訊。

public:
 override System::Data::DataTable ^ GetSchema(System::String ^ collectionName);

public override System.Data.DataTable GetSchema(string collectionName);

abstract member GetSchema : string -> System.Data.DataTable
override this.GetSchema : string -> System.Data.DataTable

Public Overrides Function GetSchema (collectionName As String) As DataTable

參數

collectionName

String

指定要回傳的結構名稱。

傳回

DataTable

DataTable A 包含結構資訊。

例外狀況

ArgumentException

collectionName 指定為空。

範例

在執行範例之前，你需要使用以下 Transact-SQL 建立範例資料庫：

USE [master]
GO

CREATE DATABASE [MySchool]
GO

USE [MySchool]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Course](
  [CourseID] [nvarchar](10) NOT NULL,
  [Year] [smallint] NOT NULL,
  [Title] [nvarchar](100) NOT NULL,
  [Credits] [int] NOT NULL,
  [DepartmentID] [int] NOT NULL,
  CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED (
    [CourseID] ASC,
    [Year] ASC
  ) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Department](
  [DepartmentID] [int] IDENTITY(1,1) NOT NULL,
  [Name] [nvarchar](50) NOT NULL,
  [Budget] [money] NOT NULL,
  [StartDate] [datetime] NOT NULL,
  [Administrator] [int] NULL,
  CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED (
    [DepartmentID] ASC
  ) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID])
  VALUES (N'C1045', 2012, N'Calculus', 4, 7)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID])
  VALUES (N'C1061', 2012, N'Physics', 4, 1)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID])
  VALUES (N'C2021', 2012, N'Composition', 3, 2)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID])
  VALUES (N'C2042', 2012, N'Literature', 4, 2)
SET IDENTITY_INSERT [dbo].[Department] ON
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator])
  VALUES (1, N'Engineering', 350000.0000, CAST(0x0000999C00000000 AS DateTime), 2)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator])
  VALUES (2, N'English', 120000.0000, CAST(0x0000999C00000000 AS DateTime), 6)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator])
  VALUES (4, N'Economics', 200000.0000, CAST(0x0000999C00000000 AS DateTime), 4)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator])
  VALUES (7, N'Mathematics', 250024.0000, CAST(0x0000999C00000000 AS DateTime), 3)
SET IDENTITY_INSERT [dbo].[Department] OFF

ALTER TABLE [dbo].[Course]
WITH CHECK ADD
  CONSTRAINT [FK_Course_Department] FOREIGN KEY([DepartmentID])
    REFERENCES [dbo].[Department] ([DepartmentID])
GO

ALTER TABLE [dbo].[Course]
CHECK CONSTRAINT [FK_Course_Department]
GO

《如何從資料庫取得結構資訊》在 Visual Studio 專案中包含此程式碼的 C# 和 Visual Basic 版本範例。

using System;
using System.Data;
using Microsoft.Data.SqlClient;

class Program
{
    static void Main(string[] args)
    {
        using (SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=MySchool;Integrated Security=True;"))
        {
            conn.Open();

            // Get the Meta Data for Supported Schema Collections  
            DataTable metaDataTable = conn.GetSchema("MetaDataCollections");

            Console.WriteLine("Meta Data for Supported Schema Collections:");
            ShowDataTable(metaDataTable, 25);
            Console.WriteLine();

            // Get the schema information of Databases in your instance  
            DataTable databasesSchemaTable = conn.GetSchema("Databases");

            Console.WriteLine("Schema Information of Databases:");
            ShowDataTable(databasesSchemaTable, 25);
            Console.WriteLine();

            // First, get schema information of all the tables in current database;  
            DataTable allTablesSchemaTable = conn.GetSchema("Tables");

            Console.WriteLine("Schema Information of All Tables:");
            ShowDataTable(allTablesSchemaTable, 20);
            Console.WriteLine();

            // You can specify the Catalog, Schema, Table Name, Table Type to get   
            // the specified table(s).  
            // You can use four restrictions for Table, so you should create a 4 members array.  
            String[] tableRestrictions = new String[4];

            // For the array, 0-member represents Catalog; 1-member represents Schema;   
            // 2-member represents Table Name; 3-member represents Table Type.   
            // Now we specify the Table Name of the table what we want to get schema information.  
            tableRestrictions[2] = "Course";

            DataTable courseTableSchemaTable = conn.GetSchema("Tables", tableRestrictions);

            Console.WriteLine("Schema Information of Course Tables:");
            ShowDataTable(courseTableSchemaTable, 20);
            Console.WriteLine();

            // First, get schema information of all the columns in current database.  
            DataTable allColumnsSchemaTable = conn.GetSchema("Columns");

            Console.WriteLine("Schema Information of All Columns:");
            ShowColumns(allColumnsSchemaTable);
            Console.WriteLine();

            // You can specify the Catalog, Schema, Table Name, Column Name to get the specified column(s).  
            // You can use four restrictions for Column, so you should create a 4 members array.  
            String[] columnRestrictions = new String[4];

            // For the array, 0-member represents Catalog; 1-member represents Schema;   
            // 2-member represents Table Name; 3-member represents Column Name.   
            // Now we specify the Table_Name and Column_Name of the columns what we want to get schema information.  
            columnRestrictions[2] = "Course";
            columnRestrictions[3] = "DepartmentID";

            DataTable departmentIDSchemaTable = conn.GetSchema("Columns", columnRestrictions);

            Console.WriteLine("Schema Information of DepartmentID Column in Course Table:");
            ShowColumns(departmentIDSchemaTable);
            Console.WriteLine();

            // First, get schema information of all the IndexColumns in current database  
            DataTable allIndexColumnsSchemaTable = conn.GetSchema("IndexColumns");

            Console.WriteLine("Schema Information of All IndexColumns:");
            ShowIndexColumns(allIndexColumnsSchemaTable);
            Console.WriteLine();

            // You can specify the Catalog, Schema, Table Name, Constraint Name, Column Name to   
            // get the specified column(s).  
            // You can use five restrictions for Column, so you should create a 5 members array.  
            String[] indexColumnsRestrictions = new String[5];

            // For the array, 0-member represents Catalog; 1-member represents Schema;   
            // 2-member represents Table Name; 3-member represents Constraint Name;4-member represents Column Name.   
            // Now we specify the Table_Name and Column_Name of the columns what we want to get schema information.  
            indexColumnsRestrictions[2] = "Course";
            indexColumnsRestrictions[4] = "CourseID";

            DataTable courseIdIndexSchemaTable = conn.GetSchema("IndexColumns", indexColumnsRestrictions);

            Console.WriteLine("Index Schema Information of CourseID Column in Course Table:");
            ShowIndexColumns(courseIdIndexSchemaTable);
            Console.WriteLine();
        }

        Console.WriteLine("Please press any key to exit...");
        Console.ReadKey();
    }

    private static void ShowDataTable(DataTable table, Int32 length)
    {
        foreach (DataColumn col in table.Columns)
        {
            Console.Write("{0,-" + length + "}", col.ColumnName);
        }
        Console.WriteLine();

        foreach (DataRow row in table.Rows)
        {
            foreach (DataColumn col in table.Columns)
            {
                if (col.DataType.Equals(typeof(DateTime)))
                {
                    Console.Write("{0,-" + length + ":d}", row[col]);
                }
                else if (col.DataType.Equals(typeof(Decimal)))
                {
                    Console.Write("{0,-" + length + ":C}", row[col]);
                }
                else {
                    Console.Write("{0,-" + length + "}", row[col]);
                }
            }
            Console.WriteLine();
        }
    }

    private static void ShowDataTable(DataTable table)
    {
        ShowDataTable(table, 14);
    }

    private static void ShowColumns(DataTable columnsTable)
    {
        var selectedRows = from info in columnsTable.AsEnumerable()
                           select new
                           {
                               TableCatalog = info["TABLE_CATALOG"],
                               TableSchema = info["TABLE_SCHEMA"],
                               TableName = info["TABLE_NAME"],
                               ColumnName = info["COLUMN_NAME"],
                               DataType = info["DATA_TYPE"]
                           };

        Console.WriteLine("{0,-15}{1,-15}{2,-15}{3,-15}{4,-15}", "TableCatalog", "TABLE_SCHEMA",
            "TABLE_NAME", "COLUMN_NAME", "DATA_TYPE");
        foreach (var row in selectedRows)
        {
            Console.WriteLine("{0,-15}{1,-15}{2,-15}{3,-15}{4,-15}", row.TableCatalog,
                row.TableSchema, row.TableName, row.ColumnName, row.DataType);
        }
    }

    private static void ShowIndexColumns(DataTable indexColumnsTable)
    {
        var selectedRows = from info in indexColumnsTable.AsEnumerable()
                           select new
                           {
                               TableSchema = info["table_schema"],
                               TableName = info["table_name"],
                               ColumnName = info["column_name"],
                               ConstraintSchema = info["constraint_schema"],
                               ConstraintName = info["constraint_name"],
                               KeyType = info["KeyType"]
                           };

        Console.WriteLine("{0,-14}{1,-11}{2,-14}{3,-18}{4,-16}{5,-8}", "table_schema", "table_name", "column_name", "constraint_schema", "constraint_name", "KeyType");
        foreach (var row in selectedRows)
        {
            Console.WriteLine("{0,-14}{1,-11}{2,-14}{3,-18}{4,-16}{5,-8}", row.TableSchema,
                row.TableName, row.ColumnName, row.ConstraintSchema, row.ConstraintName, row.KeyType);
        }
    }
}

備註

你可能需要資料庫、資料表或欄位的結構資訊。 這個範例：

• 使用 GetSchema 取得結構資訊。
• 使用結構限制來取得指定的資訊。
• 取得資料庫、資料表和部分欄位的結構資訊。

GetSchema(String, String[])

回傳此 SqlConnection 資料來源的結構資訊，並使用指定的字串作為結構名稱，並以指定的字串陣列作為限制值。

public:
 override System::Data::DataTable ^ GetSchema(System::String ^ collectionName, cli::array <System::String ^> ^ restrictionValues);

public override System.Data.DataTable GetSchema(string collectionName, string[] restrictionValues);

abstract member GetSchema : string * string[] -> System.Data.DataTable
override this.GetSchema : string * string[] -> System.Data.DataTable

Public Overrides Function GetSchema (collectionName As String, restrictionValues As String()) As DataTable

參數

collectionName

String

指定要回傳的結構名稱。

restrictionValues

String[]

一組限制值用於請求的結構。

傳回

DataTable

DataTable A 包含結構資訊。

例外狀況

ArgumentException

collectionName 指定為空。

範例

關於示範的程式碼範例 GetSchema()，請參見 GetSchema()。

備註

參數 restrictionValues 可提供 n 深度的值，這些深度由特定集合的限制集合指定。 為了設定給定限制的值，而非設定其他限制的值，你需要先將前述限制設為 ， null 然後輸入你想指定值的該限制的適當值。

例如「Tables」集合。 如果「Tables」集合有三個限制——資料庫、擁有者和資料表名稱——而你只想回傳與擁有者「Carl」相關的資料表，你需要輸入以下值：null、「Carl」。 若未傳遞限制值，則使用該限制的預設值。 這與輸入 null參數值的映射相同，而 則不同於輸入空字串取得參數值。 此時，空字串（“”）被視為指定參數的值。

另請參閱

• GetSchema()