SqlConnection.GetSchema Method

Source:

System.Data.SqlClient.notsupported.cs

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

Returns

A DataTable that contains schema information.

See also

• Obtaining Schema Information from a Database
• ADO.NET Overview

Source:

System.Data.SqlClient.notsupported.cs

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

Parameters

Returns

A DataTable that contains schema information.

Exceptions

Remarks

You may need the schema information of the database, tables or columns. This sample:

• Uses GetSchema to get schema information.

• Use schema restrictions to get the specified information.

• Gets schema information of the database, tables, and some columns.

Before you run the sample, you need to create the sample database, using the following Transact-SQL:

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

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

class Program {
   static void Main(string[] args) {

      using (SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=MySchool;Integrated Security=True;Asynchronous Processing=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);
      }
   }
}

See also

• Obtaining Schema Information from a Database
• ADO.NET Overview

Source:

System.Data.SqlClient.notsupported.cs

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

Parameters

Returns

A DataTable that contains schema information.

Exceptions

Remarks

The restrictionValues parameter can supply n depth of values, which are specified by the restrictions collection for a specific collection. In order to set values on a given restriction, and not set the values of other restrictions, you need to set the preceding restrictions to null and then put the appropriate value in for the restriction that you would like to specify a value for.

An example of this is the "Tables" collection. If the "Tables" collection has three restrictions--database, owner, and table name--and you want to get back only the tables associated with the owner "Carl", you need to pass in the following values: null, "Carl". If a restriction value is not passed in, the default values are used for that restriction. This is the same mapping as passing in null, which is different from passing in an empty string for the parameter value. In that case, the empty string ("") is considered to be the value for the specified parameter.

For a code sample demonstrating GetSchema, see GetSchema.

See also

• GetSchema()
• Obtaining Schema Information from a Database
• ADO.NET Overview