/// <summary>
/// 生成修改列的类型的语句
/// </summary>
/// <param name="op">修改列类型的实例对象</param>
protected override void Generate(AlterColumnType op)
{
//SQLite 不支持
if (op.DbType == DbType.Int32 && op.NewType == DbType.Int64)
{
//可能是自增列的类型在创建时不支持 Int64，而是以 Int32 生成了，所以这里选择忽略此种情况。
}
else
{
this.AlterColumnNotSupport(op);
}
}
protected override void Generate(AlterColumnType op)
{
using (var sql = this.Writer())
{
sql.Write("ALTER TABLE ");
sql.Write(this.Quote(op.TableName));
sql.WriteLine();
sql.Indent++;
sql.Write("ALTER COLUMN ");
this.GenerateColumnDeclaration(sql, op.ColumnName, op.NewType, op.Length, op.IsRequired, op.IsForeignKey);
this.AddRun(sql);
}
}
protected override void Generate(AlterColumnType op)
{
using (var sql = this.Writer())
{
sql.Write("ALTER TABLE ");
sql.Write(this.Quote(op.TableName));
sql.WriteLine();
sql.Indent++;
sql.Write("MODIFY ");//ORACLE 中，MODIFY 关键字后没有 COLUMN 关键字。
//Oracle 中如果可空性没有变化时，不能加到 Modify Column 之后。
bool?isRequired = null;
this.GenerateColumnDeclaration(sql, op.ColumnName, op.NewType, op.Length, isRequired, op.IsForeignKey);
this.AddRun(sql);
}
}
protected abstract void Generate(AlterColumnType op);
/// <summary>
///
/// </summary>
/// <param name="op"></param>
protected override void Generate(AlterColumnType op)
{
throw new NotImplementedException();
}