/// <summary>
/// 创建 SQL 命令
/// </summary>
/// <param name="query">查询 语句</param>
/// <returns></returns>
public CommandDefine Parse <T>(IDbQueryable <T> query)
{
IDbQueryableInfo <T> info = DbQueryParser.Parse(query);
DbQueryableInfo_Select <T> qQuery = info as DbQueryableInfo_Select <T>;
if (qQuery != null)
{
return(this.ParseSelectCommand <T>(qQuery));
}
DbQueryableInfo_Insert <T> qInsert = info as DbQueryableInfo_Insert <T>;
if (qInsert != null)
{
return(this.ParseInsertCommand <T>(qInsert));
}
DbQueryableInfo_Update <T> qUpdate = info as DbQueryableInfo_Update <T>;
if (qUpdate != null)
{
return(this.ParseUpdateCommand <T>(qUpdate));
}
DbQueryableInfo_Delete <T> qDelete = info as DbQueryableInfo_Delete <T>;
if (qDelete != null)
{
return(this.ParseDeleteCommand <T>(qDelete));
}
throw new NotImplementedException();
}
public static IDbQueryableInfo <TElement> Parse <TElement>(IDbQueryable <TElement> query, int start = 0)
{
// 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
Type type = null;
bool isDistinct = false;
bool isAny = false;
int? skip = null;
int? take = null;
int? outer = null;
List <Expression> where = new List <Expression>(); // WHERE
List <Expression> having = new List <Expression>(); // HAVING
List <DbExpression> join = new List <DbExpression>(); // JOIN
List <DbExpression> orderBy = new List <DbExpression>(); // ORDER BY
List <IDbQueryableInfo <TElement> > union = new List <IDbQueryableInfo <TElement> >();
Expression select = null; // SELECT #
DbExpression insert = null; // INSERT #
DbExpression update = null; // UPDATE #
DbExpression delete = null; // DELETE #
DbExpression groupBy = null; // GROUP BY #
DbExpression statis = null; // MAX/MIN... #
//HashSet<Expression> aliasExpressions = new HashSet<Expression>();
for (int index = start; index < query.DbExpressions.Count; ++index)
{
DbExpression curExp = query.DbExpressions[index];
// Take(n)
if (take != null)
{
outer = index;
break;
}
//if (skip != null && (index == query.DbExpressions.Count - 1 || query.DbExpressions[index + 1].DbExpressionType != DbExpressionType.Take))
if (skip != null && curExp.DbExpressionType != DbExpressionType.Take)
{
outer = index;
break;
}
switch (curExp.DbExpressionType)
{
case DbExpressionType.None:
case DbExpressionType.All:
continue;
case DbExpressionType.Any:
isAny = true;
if (curExp.Expressions != null)
{
where.Add(curExp.Expressions[0]);
}
break;
case DbExpressionType.Union:
var uQuery = (curExp.Expressions[0] as ConstantExpression).Value as IDbQueryable <TElement>;
var u = DbQueryParser.Parse(uQuery);
union.Add(u);
continue;
case DbExpressionType.GroupBy:
groupBy = curExp;
continue;
case DbExpressionType.GetTable:
type = (curExp.Expressions[0] as ConstantExpression).Value as Type;
continue;
case DbExpressionType.Average:
case DbExpressionType.Min:
case DbExpressionType.Sum:
case DbExpressionType.Max:
statis = curExp;
continue;
case DbExpressionType.Count:
statis = curExp;
if (curExp.Expressions != null)
{
where.Add(curExp.Expressions[0]);
}
continue;
case DbExpressionType.Distinct:
isDistinct = true;
continue;
case DbExpressionType.First:
case DbExpressionType.FirstOrDefault:
take = 1;
if (curExp.Expressions != null)
{
where.Add(curExp.Expressions[0]);
}
continue;
case DbExpressionType.GroupJoin:
case DbExpressionType.Join:
select = curExp.Expressions[3];
join.Add(curExp);
//aliasExpressions.Add(select);
continue;
case DbExpressionType.OrderBy:
case DbExpressionType.OrderByDescending:
orderBy.Add(curExp);
continue;
case DbExpressionType.Select:
select = curExp.Expressions[0];
//aliasExpressions.Add(select);
continue;
case DbExpressionType.SelectMany:
select = curExp.Expressions[1];
if (!curExp.Expressions[0].IsAnonymous())
{
join.Add(curExp);
}
//aliasExpressions.Add(select);
continue;
case DbExpressionType.Single:
case DbExpressionType.SingleOrDefault:
take = 1;
if (curExp.Expressions != null)
{
where.Add(curExp.Expressions[0]);
}
continue;
case DbExpressionType.Skip:
skip = (int)(curExp.Expressions[0] as ConstantExpression).Value;
continue;
case DbExpressionType.Take:
take = (int)(curExp.Expressions[0] as ConstantExpression).Value;
continue;
case DbExpressionType.ThenBy:
case DbExpressionType.ThenByDescending:
orderBy.Add(curExp);
continue;
case DbExpressionType.Where:
var predicate = groupBy == null ? where : having;
if (curExp.Expressions != null)
{
predicate.Add(curExp.Expressions[0]);
}
continue;
case DbExpressionType.Insert:
insert = curExp;
continue;
case DbExpressionType.Update:
update = curExp;
continue;
case DbExpressionType.Delete:
delete = curExp;
continue;
default:
throw new NotSupportedException(string.Format("{0} is not support.", curExp.DbExpressionType));
}
}
// 没有解析到INSERT/DELETE/UPDATE/SELECT表达式，并且没有相关统计函数，则默认选择FromType的所有字段
bool useAllColumn = insert == null && delete == null && update == null && select == null && statis == null;
if (useAllColumn)
{
select = Expression.Constant(type ?? typeof(TElement));
//aliasExpressions.Add(select);
//移到 GetTabl 中去
}
var qQuery = new DbQueryableInfo_Select <TElement>();
qQuery.FromType = type;
qQuery.Expression = new DbExpression(DbExpressionType.Select, select);
qQuery.HaveDistinct = isDistinct;
qQuery.HaveAny = isAny;
qQuery.Join = join;
qQuery.OrderBy = orderBy;
qQuery.GroupBy = groupBy;
qQuery.Skip = skip != null ? skip.Value : 0;
qQuery.Take = take != null ? take.Value : 0;
qQuery.Where = new DbExpression(DbExpressionType.Where, DbQueryParser.Combine(where));
qQuery.Having = new DbExpression(DbExpressionType.None, DbQueryParser.Combine(having));
qQuery.Statis = statis;
qQuery.Union = union;
//qQuery.AliasExpressions = aliasExpressions;
if (update != null)
{
var qUpdate = new DbQueryableInfo_Update <TElement>();
ConstantExpression expression2 = update.Expressions != null ? update.Expressions[0] as ConstantExpression : null;
if (expression2 != null)
{
qUpdate.Entity = expression2.Value;
}
else
{
qUpdate.Expression = update.Expressions[0];
}
qUpdate.SelectInfo = qQuery;
return(qUpdate);
}
if (delete != null)
{
var qDelete = new DbQueryableInfo_Delete <TElement>();
ConstantExpression expression2 = delete.Expressions != null ? delete.Expressions[0] as ConstantExpression : null;
if (expression2 != null)
{
qDelete.Entity = expression2.Value;
}
qDelete.SelectInfo = qQuery;
return(qDelete);
}
if (insert != null)
{
var qInsert = new DbQueryableInfo_Insert <TElement>();
if (insert.Expressions != null)
{
qInsert.Entity = (insert.Expressions[0] as ConstantExpression).Value;
}
qInsert.SelectInfo = qQuery;
query.DbQueryInfo = qInsert;
qInsert.Bulk = query.Bulk;
return(qInsert);
}
if (outer != null)
{
// 解析嵌套查询
var qOuter = (DbQueryableInfo_Select <TElement>)DbQueryParser.Parse <TElement>(query, outer.Value);
qOuter.Subquery = qQuery;
return(qOuter);
}
// 查询表达式
return(qQuery);
}