private IExpression Where(DataUpdateContext context, UpdateStatement statement)
{
if (context.IsMultiple || context.Criteria == null)
{
var criteria = new ConditionExpression(ConditionCombination.And);
foreach (var key in statement.Entity.Key)
{
if (!statement.Entity.GetTokens(context.ModelType).TryGet(key.Name, out var token))
{
throw new DataException($"No required primary key field values were specified for the updation '{statement.Entity.Name}' entity data.");
}
var field = statement.Table.CreateField(key);
var parameter = Expression.Parameter(field, new SchemaMember(token));
criteria.Add(Expression.Equal(field, parameter));
statement.Parameters.Add(parameter);
}
criteria.Add(statement.Where(context.Validate(), context.Aliaser));
return(criteria.Count > 0 ? criteria : null);
}
return(statement.Where(context.Validate(), context.Aliaser));
}
public IEnumerable <IStatementBase> Build(DataIncrementContext context)
{
var statement = new UpdateStatement(context.Entity);
var source = statement.From(context.Member, context.Aliaser, null, out var property);
var field = source.CreateField(property);
var value = context.Interval > 0 ?
Expression.Add(field, Expression.Constant(context.Interval)) :
Expression.Subtract(field, Expression.Constant(-context.Interval));
//添加修改字段
statement.Fields.Add(new FieldValue(field, value));
//构建WHERE子句
statement.Where = statement.Where(context.Validate(), context.Aliaser);
if (context.Source.Features.Support(Feature.Updation.Outputting))
{
statement.Returning = new ReturningClause();
statement.Returning.Append(field, ReturningClause.ReturningMode.Inserted);
}
else
{
var slave = new SelectStatement();
foreach (var from in statement.From)
{
slave.From.Add(from);
}
slave.Where = statement.Where;
slave.Select.Members.Add(field);
//注：由于从属语句的WHERE子句只是简单的指向父语句的WHERE子句，
//因此必须手动将父语句的参数依次添加到从属语句中。
foreach (var parameter in statement.Parameters)
{
slave.Parameters.Add(parameter);
}
statement.Slaves.Add(slave);
}
yield return(statement);
}