C#-操作PostgreSQL-数据库

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一、第三方类库

Npgsql提供 .NET 操作postgreSQL数据库的相关类。支持postgreSQL7.x 及以上版本。

二、自定义接口及操作类

2.1接口类

public interface IDBHelper{/// <summary>/// 执行 Transact-SQL 语句并返回受影响的行数。/// </summary>int ExecuteNonQuery(string connectionString, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 在事务中执行 Transact-SQL 语句并返回受影响的行数。/// </summary>int ExecuteNonQuery(System.Data.Common.DbTransaction trans, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 在事务中执行查询，返回DataSet/// </summary>DataSet ExecuteQuery(System.Data.Common.DbTransaction trans, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 执行查询，返回DataSet/// </summary>DataSet ExecuteQuery(string connectionString, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 在事务中执行查询，返回DataReader/// </summary>DbDataReader ExecuteReader(System.Data.Common.DbTransaction trans, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 执行查询，返回DataReader/// </summary>DbDataReader ExecuteReader(string connectionString, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 在事务中执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行。/// </summary>object ExecuteScalar(System.Data.Common.DbTransaction trans, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行。/// </summary>object ExecuteScalar(string connectionString, System.Data.CommandType cmdType, string cmdText, params System.Data.Common.DbParameter[] cmdParms);/// <summary>/// 得到数据条数/// </summary>/// <param name="tblName">表名</param>/// <param name="condition">条件(不需要where)</param>/// <returns>数据条数</returns>int GetCount(string connectionString, string tblName, string condition);}

2.2 操作类

/// <summary>/// 数据库操作基类(for PostgreSQL)/// </summary>public class PostgreHelper : IDBHelper{/// <summary>/// 得到数据条数/// </summary>public int GetCount(string connectionString, string tblName, string condition){StringBuilder sql = new StringBuilder("select count(*) from " + tblName);if (!string.IsNullOrEmpty(condition))sql.Append(" where " + condition);object count = ExecuteScalar(connectionString, CommandType.Text, sql.ToString(), null);return int.Parse(count.ToString());}/// <summary>/// 执行查询，返回DataSet/// </summary>public DataSet ExecuteQuery(string connectionString, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){using (NpgsqlConnection conn = new NpgsqlConnection(connectionString)){using (NpgsqlCommand cmd = new NpgsqlCommand()){PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms);using (NpgsqlDataAdapter da = new NpgsqlDataAdapter(cmd)){DataSet ds = new DataSet();da.Fill(ds, "ds");cmd.Parameters.Clear();return ds;}}}}/// <summary>/// 在事务中执行查询，返回DataSet/// </summary>public DataSet ExecuteQuery(DbTransaction trans, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, cmdParms);NpgsqlDataAdapter da = new NpgsqlDataAdapter(cmd);DataSet ds = new DataSet();da.Fill(ds, "ds");cmd.Parameters.Clear();return ds;}/// <summary>/// 执行 Transact-SQL 语句并返回受影响的行数。/// </summary>public int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();using (NpgsqlConnection conn = new NpgsqlConnection(connectionString)){PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms);int val = cmd.ExecuteNonQuery();cmd.Parameters.Clear();return val;}}/// <summary>/// 在事务中执行 Transact-SQL 语句并返回受影响的行数。/// </summary>public int ExecuteNonQuery(DbTransaction trans, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, cmdParms);int val = cmd.ExecuteNonQuery();cmd.Parameters.Clear();return val;}/// <summary>/// 执行查询，返回DataReader/// </summary>public DbDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();NpgsqlConnection conn = new NpgsqlConnection(connectionString);try{PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms);NpgsqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);cmd.Parameters.Clear();return rdr;}catch{conn.Close();throw;}}/// <summary>/// 在事务中执行查询，返回DataReader/// </summary>public DbDataReader ExecuteReader(DbTransaction trans, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, cmdParms);NpgsqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);cmd.Parameters.Clear();return rdr;}/// <summary>/// 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行。/// </summary>public object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();using (NpgsqlConnection connection = new NpgsqlConnection(connectionString)){PrepareCommand(cmd, connection, null, cmdType, cmdText, cmdParms);object val = cmd.ExecuteScalar();cmd.Parameters.Clear();return val;}}/// <summary>/// 在事务中执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行。/// </summary>public object ExecuteScalar(DbTransaction trans, CommandType cmdType, string cmdText,params DbParameter[] cmdParms){NpgsqlCommand cmd = new NpgsqlCommand();PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, cmdParms);object val = cmd.ExecuteScalar();cmd.Parameters.Clear();return val;}/// <summary>/// 生成要执行的命令/// </summary>/// <remarks>参数的格式：冒号+参数名</remarks>private static void PrepareCommand(DbCommand cmd, DbConnection conn, DbTransaction trans, CommandType cmdType,string cmdText, DbParameter[] cmdParms){if (conn.State != ConnectionState.Open)conn.Open();cmd.Connection = conn;cmd.CommandText = cmdText.Replace("@", ":").Replace("?", ":").Replace("[", "\"").Replace("]", "\"");if (trans != null)cmd.Transaction = trans;cmd.CommandType = cmdType;if (cmdParms != null){foreach (NpgsqlParameter parm in cmdParms){parm.ParameterName = parm.ParameterName.Replace("@", ":").Replace("?",":");cmd.Parameters.Add(parm);}}}}

三、数据库操作实例

写入实例：

IDBHelper dbHelper = new PostgreHelper();
string connectionString = "User ID=postgres;Password=admin;Server=192.168.0.226;Port=5432;Database=MonitorDB;";
string sql = "insert into [RawLog]([ProjectID],[File],[Note]) values('项目编号',@file,'备注')";string file = this.textBox1.Text;
if (!File.Exists(file)) return;//获取文件二进制流
System.IO.FileStream fs = new System.IO.FileStream(file, System.IO.FileMode.Open);
BinaryReader br = new BinaryReader(fs);
byte[] b = br.ReadBytes((int)fs.Length);
br.Close();fs.Close();int r = dbHelper.ExecuteNonQuery(connectionString, CommandType.Text,sql,new Npgsql.NpgsqlParameter("@file",raw_log.File));

注意：

1.查询语句中表名、字段名需用中括号[ ] 封起来，在操作类中会统一替换为双引号。

2.命令语句中的参数名格式为：@或？+ 参数名，在操作类中为统一替换为冒号。

3.对于二进制流、日期等特殊类型需采用2中的参数形式

4.经多次测试postgreSQL数据库只直接支持（冒号+参数名）的参数方式

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