/// <summary>
/// 生成 value 对应的 SQL 片断
/// </summary>
/// <param name="value">SQL值</param>
/// <param name="token">解析SQL命令时的参数上下文</param>
/// <param name="dbType">数据类型</param>
/// <param name="size">长度</param>
/// <param name="precision">精度</param>
/// <param name="scale">小数位</param>
/// <param name="direction">查询参数类型</param>
/// <returns></returns>
public string GetSqlValue(object value, ResolveToken token,
object dbType, int?size = null, int?precision = null, int?scale = null, ParameterDirection?direction = null)
{
// https://docs.microsoft.com/zh-cn/sql/t-sql/data-types/datetime2-transact-sql?view=sql-server-2017
// 1.Date 3个字节,DateTime 8个字节 DateTime2 <=4 6个字节 其它8个字节，外加1个字节存储精度
// 2.如果转换时没有指定数据类型的长度，则SQServer自动提供长度为30
// 3.隐式转换优先级 https://docs.microsoft.com/zh-cn/sql/t-sql/data-types/data-type-precedence-transact-sql?view=sql-server-2017
// 4.参数化查询只需要重写 CreateParameter
if (value == null)
{
return("NULL");
}
Type type = value.GetType();
if (token != null && token.Parameters != null)
{
// 参数化 ##########
if (!(value is string) && !(value is byte[]) && (value is IEnumerable))
{
return(this.GetSqlValue(value as IEnumerable, token, dbType, size, precision, scale));
}
else
{
return(this.AddParameter(value, token, dbType, size, precision, scale, direction).ParameterName);
}
}
else
{
// 非参数化 ##########
// 枚举类型
if (type.IsEnum)
{
return(this.GetSqlValueByEnum(value));
}
// Guid 类型
else if (value is Guid)
{
return(this.GetSqlValueByGuid(value));
}
// 数据类型
else if (TypeUtils.IsNumberType(type))
{
return(this.GetSqlValueByNumber(value));
}
// byte[] 类型
else if (value is byte[])
{
return(this.GetSqlValueByBytes(value));
}
// 布尔类型
else if (value is bool)
{
return(this.GetSqlValueByBoolean(value, dbType));
}
// 字符类型
else if (value is char || value is string)
{
return(this.GetSqlValueByString(value, dbType, size));
}
// 时间类型
else if (value is TimeSpan)
{
return(this.GetSqlValueByTime(value, dbType, scale));
}
// 日期类型
else if (value is DateTime)
{
return(this.GetSqlValueByDateTime(value, dbType, scale));
}
// 日期类型（带时区）
else if (value is DateTimeOffset)
{
return(this.GetSqlValueByDateTimeOffset(value, dbType, scale));
}
// 集合类型
else if (value is IEnumerable)
{
return(this.GetSqlValue(value as IEnumerable, token, dbType, size, precision, scale));
}
else
{
throw new NotSupportedException(string.Format("type {0} not supported serialize to string", type.FullName));
}
}
}
