ntext是什么数据类型，要占多少个byte？

hfbingo1 2008-02-03 03:38:56
ntext是什么数据类型，要占多少个byte？
只能用Like条件进行精确查找吗？等号（＝）好像不能哦！
...全文
1372 1 打赏 收藏 转发到动态 举报
写回复
用AI写文章
1 条回复
切换为时间正序
请发表友善的回复…
发表回复
昵称被占用了 2008-02-03
  • 打赏
  • 举报
 回复
长度可变
Like条件能精确查找
等号（＝）不行

帮助内容：

ntext、text 和 image
用于存储大型非 Unicode 字符、Unicode 字符及二进制数据的固定长度和可变长度数据类型。Unicode 数据使用 UNICODE UCS-2 字符集。

ntext

可变长度 Unicode 数据的最大长度为 230 - 1 (1,073,741,823) 个字符。存储大小是所输入字符个数的两倍（以字节为单位）。ntext 在 SQL-92 中的同义词是 national text。

text

服务器代码页中的可变长度非 Unicode 数据的最大长度为 231-1 (2,147,483,647) 个字符。当服务器代码页使用双字节字符时，存储量仍是 2,147,483,647 字节。存储大小可能小于 2,147,483,647 字节（取决于字符串）。

image

可变长度二进制数据介于 0 与 231-1 (2,147,483,647) 字节之间。

注释
下面的函数和语句可以与 ntext、text 或 image 数据一起使用。

函数 语句
DATALENGTH READTEXT
PATINDEX SET TEXTSIZE
SUBSTRING UPDATETEXT
TEXTPTR WRITETEXT
TEXTVALID


CMS.DBUtility.dll
一款特别好用的.net数据库链接通用类。 using System; using System.Collections; using System.Collections.Specialized; using System.Data; using System.Data.SqlClient; using System.Configuration; using System.Data.Common; using System.Collections.Generic; namespace CMS.DBUtility { /// /// 数据访问抽象基础类 /// Copyright (C) 2004-2008 By LiTianPing /// public abstract class DbHelperSQL { //数据库连接字符串(web.config来配置)，可以动态更改connectionString支持多数据库. public static string connectionString = PubConstant.ConnectionString; public DbHelperSQL() { } #region 公用方法 /// /// 判断是否存在某表的某个字段 /// /// 表名称 /// 列名称 /// 是否存在 public static bool ColumnExists(string tableName, string columnName) { string sql = "select count(1) from syscolumns where [id]=object_id('" + tableName + "') and [name]='" + columnName + "'"; object res = GetSingle(sql); if (res == null) { return false; } return Convert.ToInt32(res) > 0; } public static int GetMaxID(string FieldName, string TableName) { string strsql = "select max(" + FieldName + ")+1 from " + TableName; object obj = GetSingle(strsql); if (obj == null) { return 1; } else { return int.Parse(obj.ToString()); } } public static bool Exists(string strSql) { object obj = GetSingle(strSql); int cmdresult; if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } if (cmdresult == 0) { return false; } else { return true; } } /// /// 表是否存在 /// /// /// public static bool TabExists(string TableName) { string strsql = "select count(*) from sysobjects where id = object_id(N'[" + TableName + "]') and OBJECTPROPERTY(id, N'IsUserTable') = 1"; //string strsql = "SELECT count(*) FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[" + TableName + "]') AND type in (N'U')"; object obj = GetSingle(strsql); int cmdresult; if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } if (cmdresult == 0) { return false; } else { return true; } } public static bool Exists(string strSql, params SqlParameter[] cmdParms) { object obj = GetSingle(strSql, cmdParms); int cmdresult; if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { cmdresult = 0; } else { cmdresult = int.Parse(obj.ToString()); } if (cmdresult == 0) { return false; } else { return true; } } #endregion #region 执行简单SQL语句 /// /// 执行SQL语句，返回影响的记录数 /// /// SQL语句 /// 影响的记录数 public static int ExecuteSql(string SQLString) { using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand cmd = new SqlCommand(SQLString, connection)) { try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SqlClient.SqlException e) { connection.Close(); throw e; } } } } public static int ExecuteSqlByTime(string SQLString, int Times) { using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand cmd = new SqlCommand(SQLString, connection)) { try { connection.Open(); cmd.CommandTimeout = Times; int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SqlClient.SqlException e) { connection.Close(); throw e; } } } } /// /// 执行Sql和Oracle滴混合事务 /// /// SQL命令行列表 /// Oracle命令行列表 /// 执行结果 0-由于SQL造成事务失败 -1 由于Oracle造成事务失败 1-整体事务执行成功 public static int ExecuteSqlTran(List list, List oracleCmdSqlList) { using (SqlConnection conn = new SqlConnection(connectionString)) { conn.Open(); SqlCommand cmd = new SqlCommand(); cmd.Connection = conn; SqlTransaction tx = conn.BeginTransaction(); cmd.Transaction = tx; try { foreach (CommandInfo myDE in list) { string cmdText = myDE.CommandText; SqlParameter[] cmdParms = (SqlParameter[])myDE.Parameters; PrepareCommand(cmd, conn, tx, cmdText, cmdParms); if (myDE.EffentNextType == EffentNextType.SolicitationEvent) { if (myDE.CommandText.ToLower().IndexOf("count(") == -1) { tx.Rollback(); throw new Exception("违背要求"+myDE.CommandText+"必须符合select count(..的格式"); //return 0; } object obj = cmd.ExecuteScalar(); bool isHave = false; if (obj == null && obj == DBNull.Value) { isHave = false; } isHave = Convert.ToInt32(obj) > 0; if (isHave) { //引发事件 myDE.OnSolicitationEvent(); } } if (myDE.EffentNextType == EffentNextType.WhenHaveContine || myDE.EffentNextType == EffentNextType.WhenNoHaveContine) { if (myDE.CommandText.ToLower().IndexOf("count(") == -1) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "必须符合select count(..的格式"); //return 0; } object obj = cmd.ExecuteScalar(); bool isHave = false; if (obj == null && obj == DBNull.Value) { isHave = false; } isHave = Convert.ToInt32(obj) > 0; if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "返回值必须大于0"); //return 0; } if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "返回值必须等于0"); //return 0; } continue; } int val = cmd.ExecuteNonQuery(); if (myDE.EffentNextType == EffentNextType.ExcuteEffectRows && val == 0) { tx.Rollback(); throw new Exception("SQL:违背要求" + myDE.CommandText + "必须有影响行"); //return 0; } cmd.Parameters.Clear(); } string oraConnectionString = PubConstant.GetConnectionString("ConnectionStringPPC"); bool res = OracleHelper.ExecuteSqlTran(oraConnectionString, oracleCmdSqlList); if (!res) { tx.Rollback(); throw new Exception("Oracle执行失败"); // return -1; } tx.Commit(); return 1; } catch (System.Data.SqlClient.SqlException e) { tx.Rollback(); throw e; } catch (Exception e) { tx.Rollback(); throw e; } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// 多条SQL语句 public static int ExecuteSqlTran(List SQLStringList) { using (SqlConnection conn = new SqlConnection(connectionString)) { conn.Open(); SqlCommand cmd = new SqlCommand(); cmd.Connection = conn; SqlTransaction tx = conn.BeginTransaction(); cmd.Transaction = tx; try { int count = 0; for (int n = 0; n < SQLStringList.Count; n++) { string strsql = SQLStringList[n]; if (strsql.Trim().Length > 1) { cmd.CommandText = strsql; count += cmd.ExecuteNonQuery(); } } tx.Commit(); return count; } catch { tx.Rollback(); return 0; } } } /// /// 执行带一个存储过程参数的的SQL语句。 /// /// SQL语句 /// 参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加 /// 影响的记录数 public static int ExecuteSql(string SQLString, string content) { using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand cmd = new SqlCommand(SQLString, connection); System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@content", SqlDbType.NText); myParameter.Value = content; cmd.Parameters.Add(myParameter); try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SqlClient.SqlException e) { throw e; } finally { cmd.Dispose(); connection.Close(); } } } /// /// 执行带一个存储过程参数的的SQL语句。 /// /// SQL语句 /// 参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加 /// 影响的记录数 public static object ExecuteSqlGet(string SQLString, string content) { using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand cmd = new SqlCommand(SQLString, connection); System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@content", SqlDbType.NText); myParameter.Value = content; cmd.Parameters.Add(myParameter); try { connection.Open(); object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (System.Data.SqlClient.SqlException e) { throw e; } finally { cmd.Dispose(); connection.Close(); } } } /// /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例) /// /// SQL语句 /// 图像字节,数据库的字段类型为image的情况 /// 影响的记录数 public static int ExecuteSqlInsertImg(string strSQL, byte[] fs) { using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand cmd = new SqlCommand(strSQL, connection); System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@fs", SqlDbType.Image); myParameter.Value = fs; cmd.Parameters.Add(myParameter); try { connection.Open(); int rows = cmd.ExecuteNonQuery(); return rows; } catch (System.Data.SqlClient.SqlException e) { throw e; } finally { cmd.Dispose(); connection.Close(); } } } /// /// 执行一条计算查询结果语句，返回查询结果（object）。 /// /// 计算查询结果语句 /// 查询结果（object） public static object GetSingle(string SQLString) { using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand cmd = new SqlCommand(SQLString, connection)) { try { connection.Open(); object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (System.Data.SqlClient.SqlException e) { connection.Close(); throw e; } } } } public static object GetSingle(string SQLString, int Times) { using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand cmd = new SqlCommand(SQLString, connection)) { try { connection.Open(); cmd.CommandTimeout = Times; object obj = cmd.ExecuteScalar(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (System.Data.SqlClient.SqlException e) { connection.Close(); throw e; } } } } /// /// 执行查询语句，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close ) /// /// 查询语句 /// SqlDataReader public static SqlDataReader ExecuteReader(string strSQL) { SqlConnection connection = new SqlConnection(connectionString); SqlCommand cmd = new SqlCommand(strSQL, connection); try { connection.Open(); SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); return myReader; } catch (System.Data.SqlClient.SqlException e) { throw e; } } /// /// 执行查询语句，返回DataSet /// /// 查询语句 /// DataSet public static DataSet Query(string SQLString) { using (SqlConnection connection = new SqlConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); SqlDataAdapter command = new SqlDataAdapter(SQLString, connection); command.Fill(ds, "ds"); } catch (System.Data.SqlClient.SqlException ex) { throw new Exception(ex.Message); } return ds; } } public static DataSet Query(string SQLString, int Times) { using (SqlConnection connection = new SqlConnection(connectionString)) { DataSet ds = new DataSet(); try { connection.Open(); SqlDataAdapter command = new SqlDataAdapter(SQLString, connection); command.SelectCommand.CommandTimeout = Times; command.Fill(ds, "ds"); } catch (System.Data.SqlClient.SqlException ex) { throw new Exception(ex.Message); } return ds; } } #endregion #region 执行带参数的SQL语句 /// /// 执行SQL语句，返回影响的记录数 /// /// SQL语句 /// 影响的记录数 public static int ExecuteSql(string SQLString, params SqlParameter[] cmdParms) { using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand cmd = new SqlCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); int rows = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); return rows; } catch (System.Data.SqlClient.SqlException e) { throw e; } } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的SqlParameter[]） public static void ExecuteSqlTran(Hashtable SQLStringList) { using (SqlConnection conn = new SqlConnection(connectionString)) { conn.Open(); using (SqlTransaction trans = conn.BeginTransaction()) { SqlCommand cmd = new SqlCommand(); try { //循环 foreach (DictionaryEntry myDE in SQLStringList) { string cmdText = myDE.Key.ToString(); SqlParameter[] cmdParms = (SqlParameter[])myDE.Value; PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); } trans.Commit(); } catch { trans.Rollback(); throw; } } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的SqlParameter[]） public static int ExecuteSqlTran(System.Collections.Generic.List cmdList) { using (SqlConnection conn = new SqlConnection(connectionString)) { conn.Open(); using (SqlTransaction trans = conn.BeginTransaction()) { SqlCommand cmd = new SqlCommand(); try { int count = 0; //循环 foreach (CommandInfo myDE in cmdList) { string cmdText = myDE.CommandText; SqlParameter[] cmdParms = (SqlParameter[])myDE.Parameters; PrepareCommand(cmd, conn, trans, cmdText, cmdParms); if (myDE.EffentNextType == EffentNextType.WhenHaveContine || myDE.EffentNextType == EffentNextType.WhenNoHaveContine) { if (myDE.CommandText.ToLower().IndexOf("count(") == -1) { trans.Rollback(); return 0; } object obj = cmd.ExecuteScalar(); bool isHave = false; if (obj == null && obj == DBNull.Value) { isHave = false; } isHave = Convert.ToInt32(obj) > 0; if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave) { trans.Rollback(); return 0; } if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave) { trans.Rollback(); return 0; } continue; } int val = cmd.ExecuteNonQuery(); count += val; if (myDE.EffentNextType == EffentNextType.ExcuteEffectRows && val == 0) { trans.Rollback(); return 0; } cmd.Parameters.Clear(); } trans.Commit(); return count; } catch { trans.Rollback(); throw; } } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的SqlParameter[]） public static void ExecuteSqlTranWithIndentity(System.Collections.Generic.List SQLStringList) { using (SqlConnection conn = new SqlConnection(connectionString)) { conn.Open(); using (SqlTransaction trans = conn.BeginTransaction()) { SqlCommand cmd = new SqlCommand(); try { int indentity = 0; //循环 foreach (CommandInfo myDE in SQLStringList) { string cmdText = myDE.CommandText; SqlParameter[] cmdParms = (SqlParameter[])myDE.Parameters; foreach (SqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.InputOutput) { q.Value = indentity; } } PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); foreach (SqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.Output) { indentity = Convert.ToInt32(q.Value); } } cmd.Parameters.Clear(); } trans.Commit(); } catch { trans.Rollback(); throw; } } } } /// /// 执行多条SQL语句，实现数据库事务。 /// /// SQL语句的哈希表（key为sql语句，value是该语句的SqlParameter[]） public static void ExecuteSqlTranWithIndentity(Hashtable SQLStringList) { using (SqlConnection conn = new SqlConnection(connectionString)) { conn.Open(); using (SqlTransaction trans = conn.BeginTransaction()) { SqlCommand cmd = new SqlCommand(); try { int indentity = 0; //循环 foreach (DictionaryEntry myDE in SQLStringList) { string cmdText = myDE.Key.ToString(); SqlParameter[] cmdParms = (SqlParameter[])myDE.Value; foreach (SqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.InputOutput) { q.Value = indentity; } } PrepareCommand(cmd, conn, trans, cmdText, cmdParms); int val = cmd.ExecuteNonQuery(); foreach (SqlParameter q in cmdParms) { if (q.Direction == ParameterDirection.Output) { indentity = Convert.ToInt32(q.Value); } } cmd.Parameters.Clear(); } trans.Commit(); } catch { trans.Rollback(); throw; } } } } /// /// 执行一条计算查询结果语句，返回查询结果（object）。 /// /// 计算查询结果语句 /// 查询结果（object） public static object GetSingle(string SQLString, params SqlParameter[] cmdParms) { using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand cmd = new SqlCommand()) { try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); object obj = cmd.ExecuteScalar(); cmd.Parameters.Clear(); if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value))) { return null; } else { return obj; } } catch (System.Data.SqlClient.SqlException e) { throw e; } } } } /// /// 执行查询语句，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close ) /// /// 查询语句 /// SqlDataReader public static SqlDataReader ExecuteReader(string SQLString, params SqlParameter[] cmdParms) { SqlConnection connection = new SqlConnection(connectionString); SqlCommand cmd = new SqlCommand(); try { PrepareCommand(cmd, connection, null, SQLString, cmdParms); SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); cmd.Parameters.Clear(); return myReader; } catch (System.Data.SqlClient.SqlException e) { throw e; } // finally // { // cmd.Dispose(); // connection.Close(); // } } /// /// 执行查询语句，返回DataSet /// /// 查询语句 /// DataSet public static DataSet Query(string SQLString, params SqlParameter[] cmdParms) { using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand cmd = new SqlCommand(); PrepareCommand(cmd, connection, null, SQLString, cmdParms); using (SqlDataAdapter da = new SqlDataAdapter(cmd)) { DataSet ds = new DataSet(); try { da.Fill(ds, "ds"); cmd.Parameters.Clear(); } catch (System.Data.SqlClient.SqlException ex) { throw new Exception(ex.Message); } return ds; } } } private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, string cmdText, SqlParameter[] cmdParms) { if (conn.State != ConnectionState.Open) conn.Open(); cmd.Connection = conn; cmd.CommandText = cmdText; if (trans != null) cmd.Transaction = trans; cmd.CommandType = CommandType.Text;//cmdType; if (cmdParms != null) { foreach (SqlParameter parameter in cmdParms) { if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) && (parameter.Value == null)) { parameter.Value = DBNull.Value; } cmd.Parameters.Add(parameter); } } } #endregion #region 存储过程操作 /// /// 执行存储过程，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close ) /// /// 存储过程名 /// 存储过程参数 /// SqlDataReader public static SqlDataReader RunProcedure(string storedProcName, IDataParameter[] parameters) { SqlConnection connection = new SqlConnection(connectionString); SqlDataReader returnReader; connection.Open(); SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters); command.CommandType = CommandType.StoredProcedure; returnReader = command.ExecuteReader(CommandBehavior.CloseConnection); return returnReader; } /// /// 执行存储过程 /// /// 存储过程名 /// 存储过程参数 /// DataSet结果中的表名 /// DataSet public static DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName) { using (SqlConnection connection = new SqlConnection(connectionString)) { DataSet dataSet = new DataSet(); connection.Open(); SqlDataAdapter sqlDA = new SqlDataAdapter(); sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters); sqlDA.Fill(dataSet, tableName); connection.Close(); return dataSet; } } public static DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName, int Times) { using (SqlConnection connection = new SqlConnection(connectionString)) { DataSet dataSet = new DataSet(); connection.Open(); SqlDataAdapter sqlDA = new SqlDataAdapter(); sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters); sqlDA.SelectCommand.CommandTimeout = Times; sqlDA.Fill(dataSet, tableName); connection.Close(); return dataSet; } } /// /// 构建 SqlCommand 对象(用来返回一个结果集，而不是一个整数值) /// /// 数据库连接 /// 存储过程名 /// 存储过程参数 /// SqlCommand private static SqlCommand BuildQueryCommand(SqlConnection connection, string storedProcName, IDataParameter[] parameters) { SqlCommand command = new SqlCommand(storedProcName, connection); command.CommandType = CommandType.StoredProcedure; foreach (SqlParameter parameter in parameters) { if (parameter != null) { // 检查未分配值的输出参数,将其分配以DBNull.Value. if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) && (parameter.Value == null)) { parameter.Value = DBNull.Value; } command.Parameters.Add(parameter); } } return command; } /// /// 执行存储过程，返回影响的行数 /// /// 存储过程名 /// 存储过程参数 /// 影响的行数 /// public static int RunProcedure(string storedProcName, IDataParameter[] parameters, out int rowsAffected) { using (SqlConnection connection = new SqlConnection(connectionString)) { int result; connection.Open(); SqlCommand command = BuildIntCommand(connection, storedProcName, parameters); rowsAffected = command.ExecuteNonQuery(); result = (int)command.Parameters["ReturnValue"].Value; //Connection.Close(); return result; } } /// /// 创建 SqlCommand 对象实例(用来返回一个整数值) /// /// 存储过程名 /// 存储过程参数 /// SqlCommand 对象实例 private static SqlCommand BuildIntCommand(SqlConnection connection, string storedProcName, IDataParameter[] parameters) { SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters); command.Parameters.Add(new SqlParameter("ReturnValue", SqlDbType.Int, 4, ParameterDirection.ReturnValue, false, 0, 0, string.Empty, DataRowVersion.Default, null)); return command; } #endregion } }
什么是SQL数据类型？SQL数据类型总结
一、什么叫数据类型？ 人们能够非常容易地区分数字与字符，可是计算机并不会。除非是你明确地告诉它，1是数字，“汉”是文本，不然它始终没法分辨1和‘汉’的区别。因而，在每一个计算机语言里都界定了数据类型，实际上便是对常见的各种各样的数据类型进行了明确的区分。你要让计算机计算数值，就传输数字给它，你要让它处理文本，就传字符串类型给他们。 在SQL中，数据类型是一个标签，是一个有利于SQL掌握每列中期望储存什么类型的数据的手册，它也标志了SQL怎样与储存的数据进行交互。SQL中常见的数据类型有多种，本文便介绍一
java 字节 占多少位_JAVA各种类型各占多少字节,多少位
JAVA各种类型各占多少字节,多少位在Java中一共有8种基本数据类型，其中有4种整型，2种浮点类型，1种用于表示Unicode编码的字符单元的字符类型和1种用于表示真值的boolean类型。(一个字节等于8个bit)int 类型占32个字节； 4 位；short 类型占16个字节； 2位；long 类型占64个字节； 8位；float 类型占32个字节； 4位；double 类型占64个字节； ...
SQL Server 2005 数据类型比较
1. 字符串数据类型char此数据类型可存储1~8000个定长字符串，字符串长度在创建时指定；如未指定，默认为char(1)。每个字符占用1byte存储空间。nchar此数据类型可存储1~4000个定长Unicode字符串，字符串长度在创建时指定；如未指定，默认为nchar(1)。每个字符占用2bytes存储空间。varchar此数据类型可存储最大值为8000个字符的可变长字符串。可变长字符串
SQL Server 2005 常用数据类型详解
1. 字符串数据类型 char 此数据类型可存储1~8000个定长字符串，字符串长度在创建时指定；如未指定，默认为char(1)。每个字符占用1byte存储空间。 nchar 此数据类型可存储1~4000个定长Unicode字符串，字符串长度在创建时指定；如未指定，默认为nchar(1)。每个字符占用2bytes存储空间。 varchar 此数据类型可存储最大值为8000个字符的可变长
MS-SQL Server

34,576

社区成员

254,587

社区内容

发帖
与我相关
我的任务
社区描述
MS-SQL Server相关内容讨论专区
社区管理员
  • 基础类社区
  • 二月十六
  • 卖水果的net
加入社区
  • 近7日
  • 近30日
  • 至今

加载中

查看更多榜单
社区公告
暂无公告

试试用AI创作助手写篇文章吧

+ 用AI写文章