SqlConnection.GetSchema Metode

Definisi

Ruang nama:

Microsoft.Data.SqlClient

Rakitan:

Microsoft.Data.SqlClient.dll

Paket:

Microsoft.Data.SqlClient v5.2.0

Overload

GetSchema()	Mengembalikan informasi skema untuk sumber data ini SqlConnection. Untuk informasi selengkapnya tentang skema, lihat SQL Server Koleksi Skema.
GetSchema(String)	Mengembalikan informasi skema untuk sumber data ini SqlConnection menggunakan string yang ditentukan untuk nama skema.
GetSchema(String, String[])	Mengembalikan informasi skema untuk sumber data ini SqlConnection menggunakan string yang ditentukan untuk nama skema dan array string yang ditentukan untuk nilai pembatasan.

GetSchema()

Mengembalikan informasi skema untuk sumber data ini SqlConnection. Untuk informasi selengkapnya tentang skema, lihat SQL Server Koleksi Skema.

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

public override System.Data.DataTable GetSchema ();

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

Public Overrides Function GetSchema () As DataTable

Mengembalikan

DataTable

Yang DataTable berisi informasi skema.

GetSchema(String)

Mengembalikan informasi skema untuk sumber data ini SqlConnection menggunakan string yang ditentukan untuk nama skema.

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

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

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

Public Overrides Function GetSchema (collectionName As String) As DataTable

Parameter

collectionName

String

Menentukan nama skema yang akan dikembalikan.

Mengembalikan

DataTable

Yang DataTable berisi informasi skema.

Pengecualian

ArgumentException

collectionName ditentukan sebagai null.

Keterangan

Anda mungkin memerlukan informasi skema database, tabel, atau kolom. Sampel ini:

• Menggunakan GetSchema untuk mendapatkan informasi skema.

• Gunakan pembatasan skema untuk mendapatkan informasi yang ditentukan.

• Mendapatkan informasi skema database, tabel, dan beberapa kolom.

Sebelum menjalankan sampel, Anda perlu membuat database sampel, menggunakan Transact-SQL berikut:

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  

Cara Mendapatkan Informasi Skema dari Database memiliki versi C# dan Visual Basic dari sampel kode ini dalam proyek Visual Studio.

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);
        }
    }
}

GetSchema(String, String[])

Mengembalikan informasi skema untuk sumber data ini SqlConnection menggunakan string yang ditentukan untuk nama skema dan array string yang ditentukan untuk nilai pembatasan.

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

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

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

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

Parameter

collectionName

String

Menentukan nama skema yang akan dikembalikan.

restrictionValues

String[]

Sekumpulan nilai pembatasan untuk skema yang diminta.

Mengembalikan

DataTable

Yang DataTable berisi informasi skema.

Pengecualian

ArgumentException

collectionName ditentukan sebagai null.

Keterangan

Parameter restrictionValues dapat menyediakan n kedalaman nilai, yang ditentukan oleh kumpulan pembatasan untuk koleksi tertentu. Untuk mengatur nilai pada pembatasan tertentu, dan tidak mengatur nilai pembatasan lain, Anda perlu mengatur batasan sebelumnya ke null lalu menempatkan nilai yang sesuai untuk pembatasan yang ingin Anda tentukan nilainya.

Contohnya adalah koleksi "Tabel". Jika koleksi "Tabel" memiliki tiga batasan--database, pemilik, dan nama tabel--dan Anda hanya ingin mendapatkan kembali tabel yang terkait dengan pemilik "Carl", Anda perlu meneruskan nilai berikut: null, "Carl". Jika nilai pembatasan tidak diteruskan, nilai default digunakan untuk pembatasan tersebut. Ini adalah pemetaan yang sama dengan meneruskan null, yang berbeda dari meneruskan string kosong untuk nilai parameter. Dalam hal ini, string kosong ("") dianggap sebagai nilai untuk parameter yang ditentukan.

Untuk sampel kode yang menunjukkan GetSchema, lihat GetSchema.

Lihat juga

• GetSchema()