/// <summary>
/// 初始化 <see cref="ColumnExpressionVisitor"/> 类的新实例
/// </summary>
/// <param name="ag">表别名解析器</param>
/// <param name="builder">SQL 语句生成器</param>
/// <param name="tree">查询语义</param>
public ColumnExpressionVisitor(AliasGenerator ag, ISqlBuilder builder, DbQuerySelectTree tree)
: base(ag, builder)
{
_ag = ag;
_builder = builder;
_groupBy = tree.GroupBy;
_includes = tree.Includes;
_selectedColumns = new ColumnDescriptorCollection();
_visitedStack = base.VisitedStack;
}
/// <summary>
/// 生成关联子句所表示的别名列表
/// </summary>
/// <param name="tree">查询语义</param>
/// <param name="prefix">表别名前缀</param>
/// <returns></returns>
protected AliasGenerator PrepareTableAlias(DbQuerySelectTree tree, string prefix)
{
var ag = new AliasGenerator((tree.Joins != null ? tree.Joins.Count : 0) + 1, prefix);
for (int index = 0; index < (tree.Joins != null ? tree.Joins.Count : -1); index++)
{
DbExpression d = tree.Joins[index];
// [INNER/LEFT JOIN]
if (d.DbExpressionType == DbExpressionType.LeftOuterJoin || d.DbExpressionType == DbExpressionType.Join || d.DbExpressionType == DbExpressionType.RightOuterJoin)
{
this.PrepareJoinAlias(d, ag);
}
else if (d.DbExpressionType == DbExpressionType.SelectMany)
{
this.PrepareCrossAlias(d, ag);
}
}
return(ag);
}
/// <summary>
/// 初始化 <see cref="OracleColumnExpressionVisitor"/> 类的新实例
/// </summary>
/// <param name="ag">表别名解析器</param>
/// <param name="builder">SQL 语句生成器</param>
/// <param name="tree">查询语义</param>
public OracleColumnExpressionVisitor(AliasGenerator ag, ISqlBuilder builder, DbQuerySelectTree tree)
: base(ag, builder, tree)
{
_tree = tree;
_builder = builder;
}
// 构造由一对多关系产生的嵌套查询
private static DbQuerySelectTree TryParseOutQuery(DbQuerySelectTree tree)
{
if (tree == null || tree.Select == null)
{
return(tree);
}
Expression select = tree.Select.Expressions[0];
List <DbExpression> includes = tree.Includes;
Type fromType = tree.From;
// 解析导航属性 如果有 1:n 的导航属性，那么查询的结果集的主记录将会有重复记录
// 这时就需要使用嵌套语义，先查主记录，再关联导航记录
Expression expression = select;
var lambdaExpression = expression as LambdaExpression;
if (lambdaExpression != null)
{
expression = lambdaExpression.Body;
}
var initExpression = expression as MemberInitExpression;
var newExpression = expression as NewExpression;
bool hasMany = DbQueryableParser.HasMany(includes);
if (!hasMany)
{
hasMany = initExpression != null && HasMany(initExpression);
}
#region 嵌套语义
if (hasMany)
{
newExpression = initExpression != null ? initExpression.NewExpression : newExpression;
List <MemberBinding> bindings = new List <MemberBinding>();
if (initExpression != null)
{
bindings = initExpression.Bindings.ToList(a => TypeUtils.IsPrimitiveType((a.Member as System.Reflection.PropertyInfo).PropertyType));
}
if (newExpression != null || bindings.Count() > 0)
{
// 简化内层选择器，只选择最小字段，不选择导航字段，导航字段在外层加进去
initExpression = Expression.MemberInit(newExpression, bindings);
lambdaExpression = Expression.Lambda(initExpression, lambdaExpression.Parameters);
tree.Select = new DbExpression(DbExpressionType.Select, lambdaExpression);
}
tree.Includes = new List <DbExpression>(0);
var result_Query = new DbQuerySelectTree();
result_Query.From = fromType;
result_Query.Subquery = tree;
result_Query.Joins = null;
result_Query.OrderBys = null;
result_Query.Includes = includes;
result_Query.SelectHasMany = true;
result_Query.Select = new DbExpression(DbExpressionType.Select, select);
#region 排序
if (tree.OrderBys != null && tree.OrderBys.Count > 0)
{
// 是否有分页
bool havePaging = (tree.Take > 0 || tree.Skip > 0);
if (!havePaging)
{
// 如果没有分页，则OrderBy需要放在外层
result_Query.OrderBys = tree.OrderBys;
tree.OrderBys = new List <DbExpression>(0);
}
else
{
// 如果有分页，只有主表/用到的1:1从表放在内层，其它放在外层
List <DbExpression> innerOrderBy = null;
foreach (var dbExpression in tree.OrderBys)
{
hasMany = HasMany(dbExpression.Expressions[0] as LambdaExpression);
if (!hasMany)
{
if (innerOrderBy == null)
{
innerOrderBy = new List <DbExpression>();
}
innerOrderBy.Add(dbExpression);
}
}
if (innerOrderBy != null && innerOrderBy.Count > 0)
{
result_Query.OrderBys = tree.OrderBys;
tree.OrderBys = innerOrderBy;
}
}
}
#endregion
#region 分组
if (tree.GroupBy != null)
{
// 查看外层是否需要重新构造选择器。如果有分组并且有聚合函数，则需要重新构造选择器。否则外层解析不了聚合函数
// demo => line 1280
bool newSelector = bindings.Any(x => ((MemberAssignment)x).Expression.NodeType == ExpressionType.Call) || newExpression.Arguments.Any(x => x.NodeType == ExpressionType.Call);
if (newSelector)
{
ParameterExpression newParameter = null;
List <DbExpression> dbExpressions = null;
if (result_Query.Includes != null && result_Query.Includes.Count > 0)
{
dbExpressions = result_Query.Includes;
}
else if (result_Query.OrderBys != null && result_Query.OrderBys.Count > 0)
{
dbExpressions = result_Query.OrderBys;
}
if (dbExpressions != null && dbExpressions.Count > 0)
{
newParameter = (dbExpressions[0].Expressions[0] as LambdaExpression).Parameters[0];
}
// 1对多导航嵌套查询外层的的第一个表别名固定t0，参数名可随意
var parameterExpression = newParameter != null ? newParameter : Expression.Parameter(newExpression.Type, "__g");
bindings = bindings.ToList(x => (MemberBinding)Expression.Bind(x.Member, Expression.MakeMemberAccess(parameterExpression, x.Member)));
List <Expression> arguments = null;
if (newExpression.Members != null)
{
arguments = new List <Expression>(newExpression.Arguments.Count);
for (int i = 0; i < newExpression.Arguments.Count; i++)
{
var member = newExpression.Members[i];
var arg = Expression.MakeMemberAccess(parameterExpression, member);
arguments.Add(arg);
}
}
newExpression = Expression.New(newExpression.Constructor, arguments, newExpression.Members);
initExpression = Expression.MemberInit(newExpression, bindings);
lambdaExpression = Expression.Lambda(initExpression, parameterExpression);
result_Query.Select = new DbExpression(DbExpressionType.Select, lambdaExpression);
}
}
#endregion
tree = result_Query;
}
#endregion
return(tree);
}
// 解析查询语义
private static IDbQueryTree Parse(IDbQueryable source, Type elmentType, int startIndex)
{
// 目的：将query 转换成增/删/改/查
// 1、from a in context.GetTable<T>() select a 此时query里面可能没有SELECT 表达式
// 2、Take 视为一个查询的结束位，如有更多查询，应使用嵌套查询
// 3、uion 分页查询也使嵌套语义
// 4、uion 后面跟着 WHERE,GROUP BY,SELECT,JOIN语句时需要使用嵌套查询
Type fromType = null;
DbRawSql rawSql = null;
bool isDistinct = false;
bool isAny = false;
bool isSubquery = false;
int? skip = null;
int? take = null;
int? outerIndex = null;
List <DbExpression> wheres = null; // WHERE
List <DbExpression> havings = null; // HAVING
List <DbExpression> joins = null; // JOIN
List <DbExpression> orderBys = null; // ORDER BY
List <DbExpression> includes = null; // ORDER BY
List <DbQuerySelectTree> unions = null; // UNION ALL
Expression pickExpression = null;
DbExpression insert = null; // INSERT #
DbExpression update = null; // UPDATE #
DbExpression delete = null; // DELETE #
DbExpression group = null; // GROUP BY #
DbExpression aggregate = null; // SUM&MAX #
for (int index = startIndex; index < source.DbExpressions.Count; index++)
{
DbExpression item = source.DbExpressions[index];
// Take(n)
if (take != null || (skip != null && item.DbExpressionType != DbExpressionType.Take) || isDistinct || isSubquery)
{
outerIndex = index;
break;
}
#region 解析片断
switch (item.DbExpressionType)
{
case DbExpressionType.None:
case DbExpressionType.All:
continue;
case DbExpressionType.Any:
isAny = true;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
break;
case DbExpressionType.AsSubquery:
isSubquery = true;
continue;
case DbExpressionType.Union:
var constExpression = item.Expressions[0] as ConstantExpression;
var uQuery = constExpression.Value as IDbQueryable;
var u = DbQueryableParser.Parse(uQuery, constExpression.Type.GetGenericArguments()[0], 0);
if (unions == null)
{
unions = new List <DbQuerySelectTree>();
}
unions.Add((DbQuerySelectTree)u);
// 如果下一个不是 union，就使用嵌套
if (index + 1 <= source.DbExpressions.Count - 1 && source.DbExpressions[index + 1].DbExpressionType != DbExpressionType.Union)
{
isSubquery = true;
}
continue;
case DbExpressionType.Include:
if (includes == null)
{
includes = new List <DbExpression>();
}
includes.Add(item);
continue;
case DbExpressionType.GroupBy:
group = item;
continue;
case DbExpressionType.GetTable:
fromType = (item.Expressions[0] as ConstantExpression).Value as Type;
if (fromType == null)
{
string text = (item.Expressions[0] as ConstantExpression).Value as string;
if (text != null)
{
rawSql = new DbRawSql(null, text, (object[])(item.Expressions[1] as ConstantExpression).Value);
}
}
continue;
case DbExpressionType.Average:
case DbExpressionType.Min:
case DbExpressionType.Sum:
case DbExpressionType.Max:
aggregate = item;
continue;
case DbExpressionType.Count:
aggregate = item;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
continue;
case DbExpressionType.Distinct:
isDistinct = true;
continue;
case DbExpressionType.First:
case DbExpressionType.FirstOrDefault:
take = 1;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
continue;
case DbExpressionType.Join:
case DbExpressionType.LeftOuterJoin:
case DbExpressionType.RightOuterJoin:
pickExpression = item.Expressions[3];
var j = item;
// GetTable 的参数
var inner = (j.Expressions[0] as ConstantExpression).Value as IDbQueryable;
if (inner.DbExpressions.Count == 1 && inner.DbExpressions[0].DbExpressionType == DbExpressionType.GetTable)
{
// 区别 GetTable 有三个重载，这里处理指定外键路径的重载
if (inner.DbExpressions[0].Expressions.Length == 2 && (inner.DbExpressions[0].Expressions[0] as ConstantExpression).Value is Type)
{
var expressions = new Expression[item.Expressions.Length + 1];
Array.Copy(item.Expressions, expressions, item.Expressions.Length);
expressions[expressions.Length - 1] = inner.DbExpressions[0].Expressions[1];
j = new DbExpression(item.DbExpressionType, expressions);
}
}
if (joins == null)
{
joins = new List <DbExpression>();
}
joins.Add(j);
continue;
case DbExpressionType.OrderBy:
case DbExpressionType.OrderByDescending:
if (orderBys == null)
{
orderBys = new List <DbExpression>();
}
orderBys.Add(item);
continue;
case DbExpressionType.Select:
pickExpression = item.Expressions != null ? item.Expressions[0] : null;
continue;
case DbExpressionType.SelectMany:
pickExpression = item.Expressions[1];
if (IsCrossJoinExression(source.DbExpressions, item, startIndex))
{
if (joins == null)
{
joins = new List <DbExpression>();
}
joins.Add(item);
}
continue;
case DbExpressionType.Single:
case DbExpressionType.SingleOrDefault:
take = 1;
if (item.Expressions != null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
continue;
case DbExpressionType.Skip:
skip = (int)(item.Expressions[0] as ConstantExpression).Value;
continue;
case DbExpressionType.Take:
take = (int)(item.Expressions[0] as ConstantExpression).Value;
continue;
case DbExpressionType.ThenBy:
case DbExpressionType.ThenByDescending:
if (orderBys == null)
{
orderBys = new List <DbExpression>();
}
orderBys.Add(item);
continue;
case DbExpressionType.Where:
if (item.Expressions != null)
{
if (group == null)
{
if (wheres == null)
{
wheres = new List <DbExpression>();
}
wheres.Add(item);
}
else
{
if (havings == null)
{
havings = new List <DbExpression>();
}
havings.Add(item);
}
}
continue;
case DbExpressionType.Insert:
insert = item;
continue;
case DbExpressionType.Update:
update = item;
continue;
case DbExpressionType.Delete:
delete = item;
continue;
default:
throw new NotSupportedException(string.Format("{0} is not support.", item.DbExpressionType));
}
#endregion
}
// 没有解析到INSERT/DELETE/UPDATE/SELECT表达式，并且没有相关聚合函数，则默认选择 FromEntityType 的所有字段
if (insert == null && delete == null && update == null && pickExpression == null && aggregate == null)
{
pickExpression = Expression.Constant(fromType ?? elmentType);
}
DbExpression select = new DbExpression(DbExpressionType.Select, pickExpression);
if (fromType == null)
{
fromType = elmentType;
}
var result_Query = new DbQuerySelectTree();
result_Query.From = fromType;
result_Query.FromSql = rawSql;
result_Query.HasDistinct = isDistinct;
result_Query.HasAny = isAny;
result_Query.Joins = joins;
result_Query.OrderBys = orderBys;
result_Query.GroupBy = group;
result_Query.Aggregate = aggregate;
result_Query.Unions = unions;
result_Query.Includes = includes;
result_Query.Skip = skip != null ? skip.Value : 0;
result_Query.Take = take != null ? take.Value : 0;
result_Query.Select = select;
result_Query.Wheres = wheres;
result_Query.Havings = havings;
#region 更新语义
if (update != null)
{
var result_Update = new DbQueryUpdateTree();
var constantExpression = update.Expressions != null ? update.Expressions[0] as ConstantExpression : null;
if (constantExpression != null)
{
result_Update.Entity = constantExpression.Value;
}
else
{
result_Update.Expression = update.Expressions[0];
}
result_Update.Select = result_Query;
return(result_Update);
}
#endregion
#region 除语义
else if (delete != null)
{
var result_Delete = new DbQueryDeleteTree();
var constantExpression = delete.Expressions != null ? delete.Expressions[0] as ConstantExpression : null;
if (constantExpression != null)
{
result_Delete.Entity = constantExpression.Value;
}
result_Delete.Select = result_Query;
return(result_Delete);
}
#endregion
#region 插入语义
else if (insert != null)
{
var result_Insert = new DbQueryInsertTree();
if (insert.Expressions != null)
{
result_Insert.Entity = (insert.Expressions[0] as ConstantExpression).Value;
if (insert.Expressions.Length > 1)
{
result_Insert.EntityColumns = (insert.Expressions[1] as ConstantExpression).Value as IList <Expression>;
}
}
result_Insert.Select = result_Query;
result_Insert.Bulk = ((DbQueryable)source).Bulk;
return(result_Insert);
}
#endregion
#region 择语义
else if (pickExpression != null)
{
// 检查嵌套查询语义
result_Query = DbQueryableParser.TryParseOutQuery(result_Query);
}
#endregion
#region 嵌套语义
// 解析嵌套查询
if (outerIndex != null)
{
// todo => elementType ???
var outQueryTree = DbQueryableParser.Parse(source, elmentType, outerIndex.Value);
var result_Insert = outQueryTree as DbQueryInsertTree;
var result_Update = outQueryTree as DbQueryUpdateTree;
var result_Delete = outQueryTree as DbQueryDeleteTree;
if (result_Insert != null)
{
if (result_Insert.Select != null)
{
result_Insert.Select.Subquery = result_Query;
}
else
{
result_Insert.Select = result_Query;
}
return(result_Insert);
}
else if (result_Update != null)
{
if (result_Update.Select != null)
{
result_Update.Select.Subquery = result_Query;
}
else
{
result_Update.Select = result_Query;
}
return(result_Update);
}
else if (result_Delete != null)
{
if (result_Delete.Select != null)
{
result_Delete.Select.Subquery = result_Query;
}
else
{
result_Delete.Select = result_Query;
}
return(result_Delete);
}
else
{
// 指定子查询
var iterator = (DbQuerySelectTree)outQueryTree;
while (iterator.Subquery != null)
{
iterator = iterator.Subquery;
}
iterator.Subquery = result_Query;
//// ?? AsSubquery(a=>a)，那么它所有的外层字段都要基于里层的字段
//if (isSubquery && startIndex == 0)
// LimitSelector((DbQuerySelectTree)outQueryTree);
// 如果外层是统计，内层没有分页，则不需要排序
iterator = (DbQuerySelectTree)outQueryTree;
while (iterator.Subquery != null)
{
// 没有分页的嵌套统计，不需要排序
if (iterator.Aggregate != null && !(iterator.Subquery.Take > 0 || iterator.Subquery.Skip > 0) && iterator.Subquery.OrderBys != null && iterator.Subquery.OrderBys.Count > 0)
{
iterator.Subquery.OrderBys = new List <DbExpression>(0);
}
// 继续下一轮迭代
iterator = iterator.Subquery;
}
return(outQueryTree);
}
}
#endregion
// 查询表达式
return(result_Query);
}
/// <summary> /// 解析 SELECT 命令 /// </summary> /// <param name="tree"></param> /// <param name="indent">缩进</param> /// <param name="isOutQuery">是否是最外层查询</param> /// <param name="context">解析上下文</param> /// <returns></returns> protected abstract DbRawCommand TranslateSelectCommand(DbQuerySelectTree tree, int indent, bool isOutQuery, ITranslateContext context);