/// <summary>
/// 判断是否存在。
/// </summary>
/// <param name="entityType">模型实例。</param>
/// <param name="expression">条件表达式。</param>
/// <returns>返回SQL构建实例。</returns>
public virtual SqlIndentedStringBuilder Any(IEntityType entityType, Expression expression)
{
var builder = new SqlIndentedStringBuilder();
builder.Append("SELECT 1 FROM ").Append(SqlHelper.DelimitIdentifier(entityType.Table));
builder.AppendEx(Visit(expression), " WHERE {0}").Append(SqlHelper.StatementTerminator);
return(builder);
}
/// <summary>
/// 删除实例。
/// </summary>
/// <param name="entityType">模型实例。</param>
/// <param name="expression">条件表达式。</param>
/// <returns>返回SQL构建实例。</returns>
public virtual SqlIndentedStringBuilder Delete(IEntityType entityType, Expression expression)
{
var builder = new SqlIndentedStringBuilder();
builder.Append("DELETE FROM ").Append(SqlHelper.DelimitIdentifier(entityType.Table));
builder.AppendEx(Visit(expression), " WHERE {0}").Append(SqlHelper.fieldsTerminator);
return(builder);
}
/// <summary>
/// 更新实例。
/// </summary>
/// <param name="entityType">模型实例。</param>
/// <param name="expression">条件表达式。</param>
/// <param name="parameters">匿名对象。</param>
/// <returns>返回SQL构建实例。</returns>
public virtual SqlIndentedStringBuilder Update(IEntityType entityType, Expression expression, LambdaExpression parameters)
{
var builder = new SqlIndentedStringBuilder();
builder.Append("UPDATE ").Append(SqlHelper.DelimitIdentifier(entityType.Table)).Append(" SET ");
builder.Append(VisitUpdateExpression(parameters));
builder.AppendEx(Visit(expression), " WHERE {0}").Append(SqlHelper.StatementTerminator);
return(builder);
}
/// <summary>
/// 更新实例。
/// </summary>
/// <param name="entityType">模型实例。</param>
/// <param name="expression">条件表达式。</param>
/// <param name="parameters">匿名对象。</param>
/// <returns>返回SQL构建实例。</returns>
public virtual SqlIndentedStringBuilder Update(IEntityType entityType, Expression expression, object parameters)
{
var builder = new SqlIndentedStringBuilder();
builder.Append("UPDATE ").Append(SqlHelper.DelimitIdentifier(entityType.Table)).Append(" SET ");
builder.CreateObjectParameters(parameters);
builder.JoinAppend(builder.Parameters.Keys.Select(
name => $"{SqlHelper.DelimitIdentifier(name)}={SqlHelper.Parameterized(name)}"));
builder.AppendEx(Visit(expression), " WHERE {0}").Append(SqlHelper.StatementTerminator);
return(builder);
}
/// <summary>
/// 聚合函数。
/// </summary>
/// <param name="entityType">模型实例。</param>
/// <param name="method">聚合函数。</param>
/// <param name="column">聚合列。</param>
/// <param name="expression">条件表达式。</param>
/// <param name="nullColumn">当<paramref name="column"/>为空的时候，使用的值。</param>
/// <returns>返回SQL构建实例。</returns>
public virtual SqlIndentedStringBuilder Scalar(IEntityType entityType, string method, LambdaExpression column, Expression expression, string nullColumn = null)
{
if (column != null)
{
nullColumn = SqlHelper.DelimitIdentifier(column.GetPropertyAccess().Name);
}
var builder = new SqlIndentedStringBuilder();
builder.Append($"SELECT {method}({nullColumn}) FROM {SqlHelper.DelimitIdentifier(entityType.Table)}");
builder.AppendEx(Visit(expression), " WHERE {0}")
.AppendLine(SqlHelper.StatementTerminator);
return(builder);
}