## v0.9.17 (ODBC)

- 增加 FreeSql.Provider.Odbc，实现 Oracle/SqlServer/MySql 的 Odbc 访问提供；
- 增加 FreeSqlBuilder.UseConnectionString 参数 providerType，可解决因包版本冲突时，可能无法反射获得 FreeSql.Provider 对应的类型，通常这个参数不需要设置；
- 优化 MaxLength 特性，当指定为 -1 时 DbType 会分别映射类型 text/nvarchar(max)/nvarchar2(4000)；

Providers/FreeSql.Provider.Odbc/MySql/Curd/OdbcMySqlUpdate.cs

@@ -0,0 +1,140 @@
+using FreeSql.Internal;
+using FreeSql.Internal.Model;
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace FreeSql.Odbc.MySql
+{
+
+    class OdbcMySqlUpdate<T1> : Internal.CommonProvider.UpdateProvider<T1> where T1 : class
+    {
+
+        public OdbcMySqlUpdate(IFreeSql orm, CommonUtils commonUtils, CommonExpression commonExpression, object dywhere)
+            : base(orm, commonUtils, commonExpression, dywhere)
+        {
+        }
+
+        public override int ExecuteAffrows() => base.SplitExecuteAffrows(500, 3000);
+        public override Task<int> ExecuteAffrowsAsync() => base.SplitExecuteAffrowsAsync(500, 3000);
+        public override List<T1> ExecuteUpdated() => base.SplitExecuteUpdated(500, 3000);
+        public override Task<List<T1>> ExecuteUpdatedAsync() => base.SplitExecuteUpdatedAsync(500, 3000);
+
+
+        protected override List<T1> RawExecuteUpdated()
+        {
+            var sql = this.ToSql();
+            if (string.IsNullOrEmpty(sql)) return new List<T1>();
+
+            var sb = new StringBuilder();
+            sb.Append(sql).Append(" RETURNING ");
+
+            var colidx = 0;
+            foreach (var col in _table.Columns.Values)
+            {
+                if (colidx > 0) sb.Append(", ");
+                sb.Append(_commonUtils.QuoteReadColumn(col.Attribute.MapType, _commonUtils.QuoteSqlName(col.Attribute.Name))).Append(" as ").Append(_commonUtils.QuoteSqlName(col.CsName));
+                ++colidx;
+            }
+            sql = sb.ToString();
+            var dbParms = _params.Concat(_paramsSource).ToArray();
+            var before = new Aop.CurdBeforeEventArgs(_table.Type, Aop.CurdType.Update, sql, dbParms);
+            _orm.Aop.CurdBefore?.Invoke(this, before);
+            var ret = new List<T1>();
+            Exception exception = null;
+            try
+            {
+                ret = _orm.Ado.Query<T1>(_connection, _transaction, CommandType.Text, sql, dbParms);
+                ValidateVersionAndThrow(ret.Count);
+            }
+            catch (Exception ex)
+            {
+                exception = ex;
+                throw ex;
+            }
+            finally
+            {
+                var after = new Aop.CurdAfterEventArgs(before, exception, ret);
+                _orm.Aop.CurdAfter?.Invoke(this, after);
+            }
+            return ret;
+        }
+        async protected override Task<List<T1>> RawExecuteUpdatedAsync()
+        {
+            var sql = this.ToSql();
+            if (string.IsNullOrEmpty(sql)) return new List<T1>();
+
+            var sb = new StringBuilder();
+            sb.Append(sql).Append(" RETURNING ");
+
+            var colidx = 0;
+            foreach (var col in _table.Columns.Values)
+            {
+                if (colidx > 0) sb.Append(", ");
+                sb.Append(_commonUtils.QuoteReadColumn(col.Attribute.MapType, _commonUtils.QuoteSqlName(col.Attribute.Name))).Append(" as ").Append(_commonUtils.QuoteSqlName(col.CsName));
+                ++colidx;
+            }
+            sql = sb.ToString();
+            var dbParms = _params.Concat(_paramsSource).ToArray();
+            var before = new Aop.CurdBeforeEventArgs(_table.Type, Aop.CurdType.Update, sql, dbParms);
+            _orm.Aop.CurdBefore?.Invoke(this, before);
+            var ret = new List<T1>();
+            Exception exception = null;
+            try
+            {
+                ret = await _orm.Ado.QueryAsync<T1>(_connection, _transaction, CommandType.Text, sql, dbParms);
+                ValidateVersionAndThrow(ret.Count);
+            }
+            catch (Exception ex)
+            {
+                exception = ex;
+                throw ex;
+            }
+            finally
+            {
+                var after = new Aop.CurdAfterEventArgs(before, exception, ret);
+                _orm.Aop.CurdAfter?.Invoke(this, after);
+            }
+            return ret;
+        }
+
+        protected override void ToSqlCase(StringBuilder caseWhen, ColumnInfo[] primarys)
+        {
+            if (_table.Primarys.Length == 1)
+            {
+                caseWhen.Append(_commonUtils.QuoteReadColumn(_table.Primarys.First().Attribute.MapType, _commonUtils.QuoteSqlName(_table.Primarys.First().Attribute.Name)));
+                return;
+            }
+            caseWhen.Append("CONCAT(");
+            var pkidx = 0;
+            foreach (var pk in _table.Primarys)
+            {
+                if (pkidx > 0) caseWhen.Append(", ");
+                caseWhen.Append(_commonUtils.QuoteReadColumn(pk.Attribute.MapType, _commonUtils.QuoteSqlName(pk.Attribute.Name)));
+                ++pkidx;
+            }
+            caseWhen.Append(")");
+        }
+
+        protected override void ToSqlWhen(StringBuilder sb, ColumnInfo[] primarys, object d)
+        {
+            if (_table.Primarys.Length == 1)
+            {
+                sb.Append(_commonUtils.FormatSql("{0}", _table.Primarys.First().GetMapValue(d)));
+                return;
+            }
+            sb.Append("CONCAT(");
+            var pkidx = 0;
+            foreach (var pk in _table.Primarys)
+            {
+                if (pkidx > 0) sb.Append(", ");
+                sb.Append(_commonUtils.FormatSql("{0}", pk.GetMapValue(d)));
+                ++pkidx;
+            }
+            sb.Append(")");
+        }
+    }
+}