如何使用SqlConnection.GetSchema（）获取列主键约束
我有一些ADO.NET代码来动态检测数据库模式，我需要的是如何使用SqlConnection上的GetSchema方法获取唯一列约束和主键约束。 这是我的代码：
conn.Open(); SqlCommand mSqlCommand = new SqlCommand("sp_pkeys", conn); mSqlCommand.CommandType = CommandType.StoredProcedure; mSqlCommand.Parameters.Add( "@table_name", SqlDbType.NVarChar).Value = tableName; SqlDataReader mReader = mSqlCommand.ExecuteReader( (CommandBehavior.KeyInfo | CommandBehavior.SchemaOnly)); //ExecuteReader(); DataTable schema = mReader.GetSchemaTable(); mReader.Close(); conn.Close();
在SqlConnection上调用GetSchemaTable没有任何内容可以让你弄明白这一点。
您似乎可以使用IsKey列值，对于有助于唯一标识表中记录的任何内容，该值应返回true。 但是，从IsKey列的文档（强调我的）：
true：该列是行集中的一组列之一，它们一起唯一标识该行。 IsKey设置为true的列集必须唯一标识行集中的行。 不要求这组列是最小的列集。 可以从基表主键，唯一约束或唯一索引生成该组列。
因此，您不能保证它对主键本身有贡献。
现在，如果您需要的是唯一标识行的东西，那么IsKey就可以了，因为主键并不总是唯一标识行的方式（例如，您可以使用具有唯一索引的自然标识符）。 即使您具有主键和包含其他列的唯一索引，组合中所有这些列的值也将始终是唯一的。
但是，如果您特别需要查看构成主键的列，那么GetSchemaTable将不会为您提供所需的信息。 相反，您可以只调用sp_pkeys系统存储过程来查找有助于创建主键的列的名称。
如果仍有人需要我为此创建了一个函数的解决方案，Sqlcommand包含您想要获取架构信息的语句。
Public Shared Function TableFromCommand(ByVal Command As SqlCommand) As DataTable Dim Cn As SqlConnection = Nothing Dim Dt As DataTable Dim Dr As SqlDataReader Dim Column As DataColumn Dim Answer As New DataTable Try Answer.TableName = "SearchTable" Cn = New SqlConnection("Your connection string") Cn.Open() Command.Connection = Cn For Each Prm As SqlParameter In Command.Parameters If Prm.Direction = ParameterDirection.Input _ OrElse Prm.Direction = ParameterDirection.InputOutput Then Prm.Value = DBNull.Value End If Next Dr = Command.ExecuteReader(CommandBehavior.SchemaOnly Or CommandBehavior.KeyInfo) Dt = Dr.GetSchemaTable Dim Keys As New List(Of DataColumn) Dim ColumnsDic As New SortedDictionary(Of Integer, DataColumn) For Each Row As DataRow In Dt.Rows Column = New DataColumn With Column .ColumnName = Row("ColumnName").ToString .DataType = Type.GetType(Row("DataType").ToString) .AllowDBNull = CBool(Row("AllowDBNull")) .Unique = CBool(Row("IsUnique")) .ReadOnly = CBool(Row("IsReadOnly")) If Type.GetType(Row("DataType").ToString) Is GetType(String) Then .MaxLength = CInt(Row("ColumnSize")) End If If CBool(Row("IsIdentity")) = True Then .AutoIncrement = True .AutoIncrementSeed = -1 .AutoIncrementStep = -1 End If If CBool(Row("IsKey")) = True Then Keys.Add(Column) End If End With ColumnsDic.Add(CInt(Row("ColumnOrdinal")), Column) Answer.Columns.Add(Column) Next If Keys.Count > 0 Then Answer.Constraints.Add("PrimaryKey", Keys.ToArray, True) End If Catch ex As Exception MyError.Show(ex) Finally If Cn IsNot Nothing AndAlso Not Cn.State = ConnectionState.Closed Then Cn.Close() End If End Try Return Answer End Function
您可以获取primaryKeys ， UniqueKeys和ForeignKeys以及此命令返回的dataTable中列出的任何其他模式： "connection.GetSchema (" MetaDataCollections ")"
下面是一个代码，它返回primaryKeys和UniqueKeys（键名和列名）。
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public void Dotransfer() { var sourceSchema = new TableSchema(SourceConnectionString); } public class TableSchema { public TableSchema(string connectionString) { this.TableList = new List(); this.ColumnList = new List(); this.PrimaryKeyList = new List(); this.ForeignKeyList = new List(); this.UniqueKeyList = new List(); GetDataBaseSchema(connectionString); } public List TableList { get; set; } public List ColumnList { get; set; } public List PrimaryKeyList { get; set; } public List UniqueKeyList { get; set; } public List ForeignKeyList { get; set; } protected void GetDataBaseSchema(string ConnectionString) { using (SqlConnection connection = new SqlConnection(ConnectionString)) { System.Data.SqlClient.SqlConnectionStringBuilder builder = new System.Data.SqlClient.SqlConnectionStringBuilder(); builder.ConnectionString = ConnectionString; string server = builder.DataSource; string database = builder.InitialCatalog; connection.Open(); DataTable schemaTables = connection.GetSchema("Tables"); foreach (System.Data.DataRow rowTable in schemaTables.Rows) { String tableName = rowTable.ItemArray[2].ToString(); this.TableList.Add(tableName); string[] restrictionsColumns = new string[4]; restrictionsColumns[2] = tableName; DataTable schemaColumns = connection.GetSchema("Columns", restrictionsColumns); foreach (System.Data.DataRow rowColumn in schemaColumns.Rows) { string ColumnName = rowColumn[3].ToString(); this.ColumnList.Add(new Columns(){TableName= tableName, FieldName = ColumnName}); } string[] restrictionsPrimaryKey = new string[4]; restrictionsPrimaryKey[2] = tableName; DataTable schemaPrimaryKey = connection.GetSchema("IndexColumns", restrictionsColumns); foreach (System.Data.DataRow rowPrimaryKey in schemaPrimaryKey.Rows) { string indexName = rowPrimaryKey[2].ToString(); if (indexName.IndexOf("PK_") != -1) { this.PrimaryKeyList.Add(new PrimaryKey() { TableName = tableName, FieldName = rowPrimaryKey[6].ToString(), PrimaryKeyName = indexName }); } if (indexName.IndexOf("UQ_") != -1) { this.UniqueKeyList.Add(new UniqueKey() { TableName = tableName, FieldName = rowPrimaryKey[6].ToString(), UniqueKeyName = indexName }); } } string[] restrictionsForeignKeys = new string[4]; restrictionsForeignKeys[2] = tableName; DataTable schemaForeignKeys = connection.GetSchema("ForeignKeys", restrictionsColumns); foreach (System.Data.DataRow rowFK in schemaForeignKeys.Rows) { this.ForeignKeyList.Add(new ForeignKey() { ForeignName = rowFK[2].ToString(), TableName = tableName, // FieldName = rowFK[6].ToString() //There is no information }); } } } } } public class Columns { public string TableName { get; set; } public string FieldName { get; set; } } public class PrimaryKey { public string TableName { get; set; } public string PrimaryKeyName { get; set; } public string FieldName { get; set; } } public class UniqueKey { public string TableName { get; set; } public string UniqueKeyName { get; set; } public string FieldName { get; set; } } public class ForeignKey { public string TableName { get; set; } public string ForeignName { get; set; } // public string FieldName { get; set; } //There is no information }
如何在SqlConnection上调用GetSchema（）？ 使用collectionName="IndexColumns"和模式限制列表，您可以使用GetSchema（）请求所需的信息。
看到：
- GetSchema和Schema集合
- 架构限制
一旦我使用数据库名称建立了SqlConnection，以下内容对我有用：
var connectionString = string.Format("Server=.\\SQLEXPRESS;Database={0};Trusted_Connection=true", dbName); using (var sqlConnection = new SqlConnection(connectionString)) { sqlConnection.Open(); DataTable tables = sqlConnection.GetSchema("Tables"); foreach (DataRow tablesRow in tables.Rows) { string tableName = tablesRow["table_name"].ToString(); Console.WriteLine(tableName); var indexCols = sqlConnection.GetSchema("IndexColumns", new string[] {dbName, null, tableName, "PK_" + tableName, null}); foreach (DataRow indexColsRow in indexCols.Rows) Console.WriteLine(" PK: {0}", indexColsRow["column_name"]); } }