protected override void OnVisit(ExpressionVisitorContext context, TableDefinition statement)
{
if (statement.IsTemporary)
{
context.WriteLine($"CREATE TABLE #{statement.Name} (");
}
else
{
context.WriteLine($"CREATE TABLE {statement.Name} (");
}
int index = 0;
foreach (var field in statement.Fields)
{
if (index++ > 0)
{
context.WriteLine(",");
}
context.Visit(field);
}
context.WriteLine(");");
}
protected override void VisitTables(ExpressionVisitorContext context, UpdateStatement statement, IList <TableIdentifier> tables)
{
//调用基类同名方法
base.VisitTables(context, statement, tables);
/*
* 注意：由于 MySQL 的 UPDATE 语句不支持 FROM 子句，因此必须将其改写为多表修改的语法。
*/
if (statement.HasFrom)
{
foreach (var source in statement.From)
{
switch (source)
{
case TableIdentifier table:
if (!tables.Contains(table))
{
context.Write(",");
context.Visit(table);
}
break;
case JoinClause join:
if (join.Target is TableIdentifier target)
{
if (!tables.Contains(target))
{
context.Write(",");
context.Visit(target);
}
}
else
{
throw new DataException($"The {MySqlDriver.Key} driver does not support the FROM clause of the UPDATE statement contain an expression of type '{join.Target.GetType().Name}'.");
}
break;
default:
throw new NotSupportedException($"The {MySqlDriver.Key} driver does not support the FROM clause of the UPDATE statement contain an expression of type '{source.GetType().Name}'.");
}
}
}
}
protected override void VisitTables(ExpressionVisitorContext context, UpdateStatement statement, IList <TableIdentifier> tables)
{
if (tables.Count > 1)
{
throw new DataException("The generated Update statement is incorrect, The data engine does not support multi-table updates.");
}
if (string.IsNullOrEmpty(tables[0].Alias))
{
context.Visit(tables[0]);
}
else
{
context.Write(tables[0].Alias);
}
}
protected override void OnVisit(ExpressionVisitorContext context, UpsertStatement statement)
{
if (statement.Fields == null || statement.Fields.Count == 0)
{
throw new DataException("Missing required fields in the upsert statment.");
}
var index = 0;
context.Write("INSERT INTO ");
//visitor.Visit(statement.Table);
context.Write(context.Dialect.GetIdentifier(statement.Table));
context.Write(" (");
foreach (var field in statement.Fields)
{
if (index++ > 0)
{
context.Write(",");
}
//visitor.Visit(field);
context.Write(context.Dialect.GetIdentifier(field.Name));
}
index = 0;
context.WriteLine(") VALUES ");
foreach (var value in statement.Values)
{
if (index++ > 0)
{
context.Write(",");
}
if (index % statement.Fields.Count == 1)
{
context.Write("(");
}
var parenthesisRequired = value is IStatementBase;
if (parenthesisRequired)
{
context.Write("(");
}
context.Visit(value);
if (parenthesisRequired)
{
context.Write(")");
}
if (index % statement.Fields.Count == 0)
{
context.Write(")");
}
}
index = 0;
context.WriteLine(" ON DUPLICATE KEY UPDATE ");
if (statement.Updation.Count > 0)
{
foreach (var item in statement.Updation)
{
if (index++ > 0)
{
context.Write(",");
}
context.Write(context.Dialect.GetIdentifier(item.Field));
context.Write("=");
var parenthesisRequired = item.Value is IStatementBase;
if (parenthesisRequired)
{
context.Write("(");
}
context.Visit(item.Value);
if (parenthesisRequired)
{
context.Write(")");
}
}
}
else
{
foreach (var field in statement.Fields)
{
//忽略修改序列字段
if (field.Token.Property is Metadata.IDataEntitySimplexProperty simplex && simplex.Sequence != null)
{
continue;
}
if (index++ > 0)
{
context.Write(",");
}
context.Write(context.Dialect.GetIdentifier(field.Name));
context.Write("=VALUES(");
context.Write(context.Dialect.GetIdentifier(field.Name));
context.Write(")");
}
}
context.WriteLine(";");
}
protected override void OnVisit(ExpressionVisitorContext context, UpsertStatement statement)
{
const string SOURCE_ALIAS = "SRC";
const string TARGET_ALIAS = "TAR";
if (statement.Fields == null || statement.Fields.Count == 0)
{
throw new DataException("Missing required fields in the upsert statment.");
}
context.Write("MERGE INTO ");
context.Visit(statement.Table);
//visitor.Output.Append(" AS " + TARGET_ALIAS);
context.WriteLine(" USING (SELECT ");
for (int i = 0; i < statement.Values.Count; i++)
{
if (i > 0)
{
context.Write(",");
}
context.Visit(statement.Values[i]);
}
context.WriteLine(") AS " + SOURCE_ALIAS + " (");
for (int i = 0; i < statement.Fields.Count; i++)
{
if (i > 0)
{
context.Write(",");
}
context.Write("[" + statement.Fields[i].Name + "]");
}
context.WriteLine(") ON");
for (int i = 0; i < statement.Entity.Key.Length; i++)
{
var field = Metadata.DataEntityPropertyExtension.GetFieldName(statement.Entity.Key[i], out _);
if (i > 0)
{
context.Write(" AND ");
}
if (string.IsNullOrEmpty(statement.Table.Alias))
{
context.Write($"[{field}]={SOURCE_ALIAS}.[{field}]");
}
else
{
context.Write($"{statement.Table.Alias}.[{field}]={SOURCE_ALIAS}.[{field}]");
}
}
if (statement.Updation.Count > 0)
{
context.WriteLine();
context.Write("WHEN MATCHED");
if (statement.Where != null)
{
context.WriteLine(" AND ");
context.Visit(statement.Where);
}
context.WriteLine(" THEN");
context.Write("\tUPDATE SET ");
int index = 0;
foreach (var item in statement.Updation)
{
if (index++ > 0)
{
context.Write(",");
}
context.Visit(item.Field);
context.Write("=");
var parenthesisRequired = item.Value is IStatementBase;
if (parenthesisRequired)
{
context.Write("(");
}
context.Visit(item.Value);
if (parenthesisRequired)
{
context.Write(")");
}
}
}
context.WriteLine();
context.WriteLine("WHEN NOT MATCHED THEN");
context.Write("\tINSERT (");
for (int i = 0; i < statement.Fields.Count; i++)
{
if (i > 0)
{
context.Write(",");
}
context.Write(context.Dialect.GetIdentifier(statement.Fields[i]));
}
context.Write(") VALUES (");
for (int i = 0; i < statement.Fields.Count; i++)
{
if (i > 0)
{
context.Write(",");
}
context.Write(SOURCE_ALIAS + ".[" + statement.Fields[i].Name + "]");
}
context.Write(")");
//输出返回子句
this.VisitOutput(context, statement.Returning);
context.WriteLine(";");
}
