// 创建 SELECT 命令
RawCommand ResolveSelectCommandImpl(IDbQueryableInfo_Select dbQuery, int indent, bool isOuter, ResolveToken token)
{
// 说明：
// 1.OFFSET 前必须要有 'ORDER BY'，即 'Skip' 子句前必须使用 'OrderBy' 子句
// 2.在有聚合函数的<MAX,MIN...>情况下，如果有 'Distinct' 'GroupBy' 'Skip' 'Take' 子句，则需要使用嵌套查询
// 3.'Any' 子句将翻译成 IF EXISTS...
// 4.分组再分页时需要使用嵌套查询，此时子查询不需要 'OrderBy' 子句，但最外层则需要
// 5.'Skip' 'Take' 子句视为语义结束符，在其之后的子句将使用嵌套查询
// 6.导航属性中有 1:n 关系的，需要使用嵌套查询，否则分页查询会有问题
// 导航属性中有1:n关系，只统计主表
// 例：AccountList = a.Client.AccountList,
var subQuery = dbQuery.Subquery as IDbQueryableInfo_Select;
if (dbQuery.HasMany && subQuery != null && subQuery.Aggregate != null)
{
dbQuery = subQuery;
}
bool useStatis = dbQuery.Aggregate != null;
bool useNesting = dbQuery.HasDistinct || dbQuery.GroupBy != null || dbQuery.Skip > 0 || dbQuery.Take > 0;
string alias0 = token != null && !string.IsNullOrEmpty(token.AliasPrefix) ? (token.AliasPrefix + "0") : "t0";
// 没有聚合函数或者使用 'Skip' 子句，则解析OrderBy
// 导航属性如果使用嵌套，除非有 TOP 或者 OFFSET 子句，否则不能用ORDER BY
bool useOrderBy = (!useStatis || dbQuery.Skip > 0) && !dbQuery.HasAny && (!dbQuery.IsParsedByMany || (dbQuery.Skip > 0 || dbQuery.Take > 0));
TableAlias aliases = this.PrepareTableAlias(dbQuery, token);
var result = new MappingCommand(this, aliases, token)
{
HasMany = dbQuery.HasMany
};
ISqlBuilder jf = result.JoinFragment;
ISqlBuilder wf = result.WhereFragment;
jf.Indent = indent;
#region 嵌套查询
if (useStatis && useNesting)
{
// SELECT
jf.Append("SELECT ");
jf.AppendNewLine();
// SELECT COUNT(1)
var visitor_ = new AggregateExpressionVisitor(this, aliases, dbQuery.Aggregate, dbQuery.GroupBy, alias0);
visitor_.Write(jf);
result.AddNavMembers(visitor_.NavMembers);
// SELECT COUNT(1) FROM
jf.AppendNewLine();
jf.Append("FROM ( ");
indent += 1;
jf.Indent = indent;
}
#endregion
#region 择子句
// SELECT 子句
if (jf.Indent > 0)
{
jf.AppendNewLine();
}
jf.Append("SELECT ");
if (dbQuery.HasAny)
{
jf.Append("CASE WHEN COUNT(1) = 1 THEN 1 ELSE 0 END FROM (");
indent += 1;
jf.Indent = indent;
jf.AppendNewLine();
jf.Append("SELECT 1 ");
}
if (useStatis && !useNesting)
{
// 如果有聚合函数，并且不是嵌套的话，则直接使用SELECT <MAX,MIN...>，不需要解析选择的字段
jf.AppendNewLine();
var visitor_ = new AggregateExpressionVisitor(this, aliases, dbQuery.Aggregate, dbQuery.GroupBy);
visitor_.Write(jf);
result.AddNavMembers(visitor_.NavMembers);
}
else
{
// DISTINCT 子句
if (dbQuery.HasDistinct)
{
jf.Append("DISTINCT ");
}
#region 择字段
if (!dbQuery.HasAny)
{
// SELECT 范围
var visitor2 = new SQLiteColumnExpressionVisitor(this, aliases, dbQuery);
visitor2.Write(jf);
result.PickColumns = visitor2.PickColumns;
result.PickColumnText = visitor2.PickColumnText;
result.PickNavDescriptors = visitor2.PickNavDescriptors;
result.AddNavMembers(visitor2.NavMembers);
}
#endregion
}
#endregion
#region 顺序解析
// FROM 子句
jf.AppendNewLine();
jf.Append("FROM ");
if (dbQuery.Subquery != null)
{
// 子查询
jf.Append('(');
RawCommand cmd = this.ResolveSelectCommandImpl(dbQuery.Subquery, indent + 1, false, token);
jf.Append(cmd.CommandText);
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias0);
jf.Append(' ');
}
else
{
var typeRuntime = TypeRuntimeInfoCache.GetRuntimeInfo(dbQuery.FromType);
jf.AppendMember(typeRuntime.TableName, !typeRuntime.IsTemporary);
jf.Append(' ');
jf.Append(alias0);
jf.Append(' ');
}
// LEFT<INNER> JOIN 子句
ExpressionVisitorBase visitor = new JoinExpressionVisitor(this, aliases, dbQuery.Joins);
visitor.Write(jf);
wf.Indent = jf.Indent;
// WHERE 子句
visitor = new WhereExpressionVisitor(this, aliases, dbQuery.Where);
visitor.Write(wf);
result.AddNavMembers(visitor.NavMembers);
// GROUP BY 子句
visitor = new GroupByExpressionVisitor(this, aliases, dbQuery.GroupBy);
visitor.Write(wf);
result.AddNavMembers(visitor.NavMembers);
// HAVING 子句
visitor = new HavingExpressionVisitor(this, aliases, dbQuery.Having, dbQuery.GroupBy);
visitor.Write(wf);
result.AddNavMembers(visitor.NavMembers);
// ORDER 子句
if (dbQuery.OrderBys.Count > 0 && useOrderBy)
{
visitor = new OrderByExpressionVisitor(this, aliases, dbQuery.OrderBys, dbQuery.GroupBy);
visitor.Write(wf);
result.AddNavMembers(visitor.NavMembers);
}
#endregion
#region 分页查询
if (dbQuery.Take > 0)
{
wf.AppendNewLine().AppendFormat("LIMIT {0}", this.DbValue.GetSqlValue(dbQuery.Take, token));
}
else if (dbQuery.Take == 0 && dbQuery.Skip > 0)
{
wf.AppendNewLine().AppendFormat("LIMIT {0}", this.DbValue.GetSqlValue(-1, token));
}
if (dbQuery.Skip > 0)
{
wf.AppendFormat(" OFFSET {0}", this.DbValue.GetSqlValue(dbQuery.Skip, token));
}
#endregion
#region 嵌套查询
if (useStatis && useNesting)
{
result.CombineFragments();
indent -= 1;
jf.Indent = indent;
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias0);
}
#endregion
#region 嵌套导航
// TODO Include 从表，没分页，OrderBy 报错
if (dbQuery.HasMany && subQuery != null && subQuery.OrderBys.Count > 0 && subQuery.Aggregate == null && !(subQuery.Skip > 0 || subQuery.Take > 0))
{
result.CombineFragments();
visitor = new OrderByExpressionVisitor(this, aliases, subQuery.OrderBys);//, null, "t0");
visitor.Write(jf);
}
#endregion
#region 并集查询
// UNION 子句
if (dbQuery.Unions != null && dbQuery.Unions.Count > 0)
{
result.CombineFragments();
for (int index = 0; index < dbQuery.Unions.Count; index++)
{
jf.AppendNewLine();
jf.Append("UNION ALL");
if (indent == 0)
{
jf.AppendNewLine();
}
RawCommand cmd = this.ResolveSelectCommand(dbQuery.Unions[index], indent, isOuter, token);
jf.Append(cmd.CommandText);
}
}
#endregion
#region Any 子句
// 'Any' 子句
if (dbQuery.HasAny)
{
// 产生 WHERE 子句
result.CombineFragments();
// 如果没有分页，则显式指定只查一笔记录
if (dbQuery.Take == 0 && dbQuery.Skip == 0)
{
jf.AppendNewLine();
jf.Append("LIMIT 1");
}
indent -= 1;
jf.Indent = indent;
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias0);
}
#endregion
return(result);
}
// 创建 SELECT 命令
private DbRawCommand TranslateSelectCommandImpl(DbQuerySelectTree tree, int indent, bool isOutermost, ITranslateContext context)
{
// 说明：
// 1.OFFSET 前必须要有 'ORDER BY'，即 'Skip' 子句前必须使用 'OrderBy' 子句
// 2.在有聚合函数的<MAX,MIN...>情况下，如果有 'Distinct' 'GroupBy' 'Skip' 'Take' 子句，则需要使用嵌套查询
// 3.'Any' 子句将翻译成 IF EXISTS...
// 4.分组再分页时需要使用嵌套查询，此时子查询不需要 'OrderBy' 子句，但最外层则需要
// 5.'Skip' 'Take' 子句视为语义结束符，在其之后的子句将使用嵌套查询
// 6.导航属性中有 1:n 关系的，需要使用嵌套查询，否则分页查询会有问题
// 导航属性中有1:n关系，只统计主表
// 例：AccountList = a.Client.AccountList,
var subquery = tree.Subquery as DbQuerySelectTree;
if (tree.SelectHasMany && subquery != null && subquery.Aggregate != null)
{
tree = subquery;
}
var srcDbExpressionType = context.CurrentExpressionType;
var srcIsOutermost = context.CurrentIsOutermost;
if (srcDbExpressionType == null)
{
context.CurrentExpressionType = DbExpressionType.Select;
}
if (srcIsOutermost == null || !isOutermost)
{
context.CurrentIsOutermost = isOutermost;
}
bool useAggregate = tree.Aggregate != null;
// 没有聚合函数或者使用 'Skip' 子句，则解析OrderBy
// 导航属性如果使用嵌套，除非有 TOP 或者 OFFSET 子句，否则不能用ORDER BY
// 第一层的表别名
string alias = context != null && !string.IsNullOrEmpty(context.AliasPrefix) ? (context.AliasPrefix + "0") : "t0";
bool useSubquery = tree.HasDistinct || tree.GroupBy != null || tree.Skip > 0 || tree.Take > 0;
bool useOrderBy = (!useAggregate || tree.Skip > 0) && !tree.HasAny && (!tree.SelectHasMany || (tree.Skip > 0 || tree.Take > 0));
AliasGenerator ag = this.PrepareTableAlias(tree, context != null ? context.AliasPrefix : null);
var result = new DbSelectCommand(context, ag, tree.SelectHasMany);
ISqlBuilder jf = result.JoinFragment;
ISqlBuilder wf = result.WhereFragment;
jf.Indent = indent;
#region 嵌套查询
if (useAggregate && useSubquery)
{
// SELECT
jf.Append("SELECT ");
jf.AppendNewLine();
// SELECT COUNT(1)
var visitor = new AggregateExpressionVisitor(ag, jf, tree.GroupBy, alias);
visitor.Visit(tree.Aggregate);
result.AddNavMembers(visitor.NavMembers);
// SELECT COUNT(1) FROM
jf.AppendNewLine();
jf.Append("FROM ( ");
indent += 1;
jf.Indent = indent;
context.CurrentIsOutermost = false;
}
#endregion
#region 择子句
// SELECT 子句
if (jf.Indent > 0)
{
jf.AppendNewLine();
}
jf.Append("SELECT ");
if (tree.HasAny)
{
jf.Append("CASE WHEN COUNT(1) = 1 THEN 1 ELSE 0 END FROM (");
indent += 1;
jf.Indent = indent;
jf.AppendNewLine();
jf.Append("SELECT 1 ");
}
if (useAggregate && !useSubquery)
{
// 如果有聚合函数，并且不是嵌套的话，则直接使用SELECT <MAX,MIN...>，不需要解析选择的字段
jf.AppendNewLine();
var visitor = new AggregateExpressionVisitor(ag, jf, tree.GroupBy, null);
visitor.Visit(tree.Aggregate);
result.AddNavMembers(visitor.NavMembers);
}
else
{
// DISTINCT 子句
if (tree.HasDistinct)
{
jf.Append("DISTINCT ");
}
#region 择字段
if (!tree.HasAny)
{
// SELECT 范围
var visitor = new SQLiteColumnExpressionVisitor(ag, jf, tree);
visitor.Visit(tree.Select);
result.SelectedColumns = visitor.SelectedColumns;
result.SelectedColumnText = visitor.SelectedColumnText;
result.SelectedNavs = visitor.SelectedNavDescriptors;
result.AddNavMembers(visitor.NavMembers);
}
#endregion
}
#endregion
#region 顺序解析
// FROM 子句
jf.AppendNewLine();
jf.Append("FROM ");
if (tree.Subquery != null)
{
// 子查询
jf.Append('(');
DbRawCommand cmd = this.TranslateSelectCommandImpl(tree.Subquery, indent + 1, false, context);
jf.Append(cmd.CommandText);
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias);
jf.Append(' ');
}
else if (tree.FromSql != null)
{
if (tree.FromSql.DbContext == null)
{
tree.FromSql.DbContext = context.DbContext;
}
DbRawSql rawSql = tree.FromSql;
// 解析参数
object[] args = null;
if (rawSql.Parameters != null)
{
args = rawSql.Parameters.Select(x => this.Constor.GetSqlValue(x, context)).ToArray();
}
string sql = rawSql.CommandText;
if (args != null && args.Length > 0)
{
sql = string.Format(sql, args);
}
// 子查询
jf.Append('(');
var cmd = new DbRawCommand(sql, context.Parameters, CommandType.Text);
jf.Append(cmd.CommandText);
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias);
jf.Append(' ');
}
else
{
var typeRuntime = TypeRuntimeInfoCache.GetRuntimeInfo(tree.From);
jf.AppendTable(typeRuntime.TableSchema, typeRuntime.TableName, typeRuntime.IsTemporary);
jf.Append(' ');
jf.Append(alias);
jf.Append(' ');
}
// LEFT<INNER> JOIN 子句
if (tree.Joins != null)
{
var visitor = new JoinExpressionVisitor(ag, jf);
visitor.Visit(tree.Joins);
}
wf.Indent = jf.Indent;
// WHERE 子句
if (tree.Wheres != null)
{
var visitor = new WhereExpressionVisitor(ag, wf);
visitor.Visit(tree.Wheres);
result.AddNavMembers(visitor.NavMembers);
}
// GROUP BY 子句
if (tree.GroupBy != null)
{
var visitor = new GroupByExpressionVisitor(ag, wf);
visitor.Visit(tree.GroupBy);
result.AddNavMembers(visitor.NavMembers);
}
// HAVING 子句
if (tree.Havings != null)
{
var visitor = new HavingExpressionVisitor(ag, wf, tree.GroupBy);
visitor.Visit(tree.Havings);
result.AddNavMembers(visitor.NavMembers);
}
// ORDER 子句
if (tree.OrderBys != null && tree.OrderBys.Count > 0 && useOrderBy)
{
var visitor = new OrderByExpressionVisitor(ag, wf, tree.GroupBy, null);
visitor.Visit(tree.OrderBys);
result.AddNavMembers(visitor.NavMembers);
}
#endregion
#region 分页查询
if (tree.Take > 0)
{
wf.AppendNewLine().AppendFormat("LIMIT {0}", this.Constor.GetSqlValue(tree.Take, context));
}
else if (tree.Take == 0 && tree.Skip > 0)
{
wf.AppendNewLine().AppendFormat("LIMIT {0}", this.Constor.GetSqlValue(-1, context));
}
if (tree.Skip > 0)
{
wf.AppendFormat(" OFFSET {0}", this.Constor.GetSqlValue(tree.Skip, context));
}
#endregion
#region 嵌套查询
if (useAggregate && useSubquery)
{
result.CombineFragments();
indent -= 1;
jf.Indent = indent;
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias);
}
#endregion
#region 嵌套导航
// TODO Include 从表，没分页，OrderBy 报错
if (tree.SelectHasMany && subquery.Aggregate == null &&
subquery != null && subquery.OrderBys != null && subquery.OrderBys.Count > 0 && !(subquery.Skip > 0 || subquery.Take > 0))
{
result.CombineFragments();
var visitor = new OrderByExpressionVisitor(ag, jf, null, null);
visitor.Visit(subquery.OrderBys);
}
#endregion
#region 并集查询
// UNION 子句
if (tree.Unions != null && tree.Unions.Count > 0)
{
result.CombineFragments();
for (int index = 0; index < tree.Unions.Count; index++)
{
jf.AppendNewLine();
jf.Append("UNION ALL");
if (indent == 0)
{
jf.AppendNewLine();
}
DbRawCommand cmd = this.TranslateSelectCommand(tree.Unions[index], indent, isOutermost, context);
jf.Append(cmd.CommandText);
}
}
#endregion
#region Any 子句
// 'Any' 子句
if (tree.HasAny)
{
// 产生 WHERE 子句
result.CombineFragments();
// 如果没有分页，则显式指定只查一笔记录
if (tree.Take == 0 && tree.Skip == 0)
{
jf.AppendNewLine();
jf.Append("LIMIT 1");
}
indent -= 1;
jf.Indent = indent;
jf.AppendNewLine();
jf.Append(") ");
jf.Append(alias);
}
#endregion
#region 还原状态
context.CurrentExpressionType = srcDbExpressionType;
context.CurrentIsOutermost = srcIsOutermost;
#endregion
return(result);
}
