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156 lines
5.5 KiB
156 lines
5.5 KiB
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace FireBirdUtil.SqlUtils
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{
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public class SqlUtil
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{
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/// <summary>
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/// 判断表是否存在的SQL语句
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/// <para>执行该sql语句后，结果为1时，表示表存在；否则不存在（小于1）</para>
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/// </summary>
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/// <param name="tableName">表名</param>
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public static string GetJudgeTableExistSql(string tableName)//查询结果为1时，表示表存在；否则不存在（小于1）
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{
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return "select count(*) from rdb$relations where rdb$relation_name='" + tableName.ToUpper() + "' AND RDB$VIEW_SOURCE IS NULL";
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}
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/// <summary>
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/// 创建表的SQL语句
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/// </summary>
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/// <param name="tableName">表名</param>
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/// <param name="tableParams">所有字段的参数。如：uid int,uname varchar(20)</param>
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public static string GetCreateTableSql(string tableName, string tableParams)
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{
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return "create table " + tableName + " (" + tableParams + ")";//tableParams如:“uid int,uname varchar(20)”
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}
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/// <summary>
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/// 插入一条数据的SQL语句
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/// </summary>
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/// <param name="tableName">表名</param>
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/// <param name="fieldsValues">一条数据的信息:Key为字段，Value为字段对应的值</param>
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public static string GetInsertSql(string tableName, IDictionary<string, object> fieldsValues)
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{
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string insertSql = "insert into {0} ({1}) values ({2})";
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insertSql = string.Format(insertSql, tableName, string.Join(", ", fieldsValues.Keys), "'" + string.Join("', '", fieldsValues.Values) + "'");
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return insertSql;
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}
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/// <summary>
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/// 删除表
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/// </summary>
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/// <param name="tableName">表名</param>
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public static string GetDropSql(string tableName)//TODO:未测试
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{
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return "drop table " + tableName;
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}
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/// <summary>
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/// 删除表的所有数据
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/// </summary>
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/// <param name="tableName">表名</param>
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public static string GetDeleteSql(string tableName)
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{
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return "delete from " + tableName;
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}
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/// <summary>
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/// 删除符合条件的数据
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/// </summary>
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/// <param name="tableName">表名</param>
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/// <param name="conditions">以where打头的条件</param>
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public static string GetDeleteSql(string tableName, string conditions)
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{
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return "delete from " + tableName + " " + conditions;
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}
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//delete from table1 where id=1 or id=2
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//delete from table1 where id in (3,4,5)
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//delete from table1 where age is null
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//delete from table1 where age is null and id<10
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/// <summary>
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/// 将符合条件的数据行的指定字段的值更新//不能处理将一个字段的值赋给另一个字段
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/// </summary>
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/// <param name="newValues">新值：Key为字段名，Value为新值</param>
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/// <param name="conditions">以where打头的条件</param>
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public static string GetUpdateSql(string tableName, Dictionary<string, object> newValues, string conditions)
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{
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List<string> setValueString = new List<string>();
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foreach (var item in newValues) {
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setValueString.Add(item.Key + "=" + UpdateValueToString(item.Value));
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}
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return "update " + tableName + " set " + string.Join(", ", setValueString) + " " + conditions;
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}
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private static string UpdateValueToString(object obj)
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{
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return "'" + obj.ToString() + "'";
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}
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/// <summary>
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/// 获取自增变量名。说明：长度是有限制的，好像最长是31个字符
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/// </summary>
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/// <param name="tableName">表名</param>
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internal static string GetGeneratorName(string tableName)
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{
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return tableName + "_gen";
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}
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/// <summary>
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/// 创建自增变量的SQL语句
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/// </summary>
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/// <param name="tableName">表名</param>
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public static string GetSql_AddGenerator(string tableName)
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{
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return "create generator " + GetGeneratorName(tableName);
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}
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/// <summary>
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/// 删除自增变量
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/// </summary>
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/// <param name="tableName">表名</param>
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public static string GetSql_DropGenerator(string tableName)
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{
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return "drop generator " + GetGeneratorName(tableName);
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}
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/// <summary>
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/// 查找指定自增变量的数量（用于判断是否存在指定自增变量）
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/// </summary>
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/// <param name="tableName">表名</param>
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public static string GetSql_SelectGeneratorCount(string tableName)
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{
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return string.Format("select count(*) from rdb$generators where rdb$generator_name='{0}'", GetGeneratorName(tableName).ToUpper());
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}
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/// <summary>
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/// 创建字段自增功能的SQL语句（通过添加触发器实现）
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/// <para>字段类型不是数字类型时，还有强制转换类型</para>
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/// </summary>
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/// <param name="tableName">表名</param>
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/// <param name="fieldName">字段名</param>
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/// <param name="AutoIncreasedFieldTypeIfNotNum">强制转换后的类型。为空则不转换</param>
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public static string GetSql_AddAutoIncreaseTrigger(string tableName, string fieldName, string AutoIncreasedFieldTypeIfNotNum)
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{//TODO:未测试AutoIncreasedFieldTypeIfNotNum不为空的情况
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string generatorName = GetGeneratorName(tableName);
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string triggerName = tableName + "_increaseID";
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string newValue = string.Format("gen_id({0}, 1)", generatorName);
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if (!string.IsNullOrEmpty(AutoIncreasedFieldTypeIfNotNum))
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newValue = string.Format("cast({0} as {1})", newValue, AutoIncreasedFieldTypeIfNotNum);
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string sql = @"
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create trigger {1} for {2} active before insert
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as
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begin
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if ((new.{3} is null) or (new.{3} = 0)) then
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begin
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new.{3} = {4};
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end
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end
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";//TODO:需不需要判读是否为0？
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return string.Format(sql, generatorName, triggerName, tableName, fieldName, newValue);
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}
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}
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}
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