/// <summary>
/// 访问 IsNullOrEmpty 方法
/// </summary>
/// <param name="m">方法表达式</param>
protected override Expression VisitIsNullOrEmpty(MethodCallExpression m)
{
_builder.Append("ISNULL(");
_visitor.Visit(m.Arguments[0]);
_builder.Append(",");
bool isUnicode = SqlServerUtils.IsUnicode(_visitedMark.Current);
string empty = isUnicode ? "N''" : "''";
_builder.Append(empty);
_builder.Append(") = ");
_builder.Append(empty);
return(m);
}
/// <summary>
/// 访问 string.Contains 方法
/// </summary>
/// <param name="m">方法表达式</param>
protected override Expression VisitStringContains(MethodCallExpression m)
{
// https://www.cnblogs.com/yangmingyu/p/6928209.html
// 对于其他的特殊字符：'^'， '-'， ']' 因为它们本身在包含在 '[]' 中使用，所以需要用另外的方式来转义，于是就引入了 like 中的 escape 子句，另外值得注意的是：escape 可以转义所有的特殊字符。
// EF 的 Like 不用参数化...
_visitor.Visit(m.Object);
if (this.NotOperands != null && this.NotOperands.Contains(m))
{
_builder.Append(" NOT");
}
_builder.Append(" LIKE ");
if (m.Arguments[0].CanEvaluate())
{
ColumnAttribute column = null;
bool isUnicode = SqlServerUtils.IsUnicode(_visitedMark.Current, out column);
string value = _constor.GetSqlValue(m.Arguments[0].Evaluate().Value, _builder.TranslateContext, column);
if (!_builder.Parameterized && value != null)
{
value = value.TrimStart('N').Trim('\'');
}
if (_builder.Parameterized)
{
_builder.Append("(");
_builder.Append("'%' + ");
_builder.Append(value);
_builder.Append(" + '%'");
_builder.Append(")");
}
else
{
if (isUnicode)
{
_builder.Append('N');
}
_builder.Append("'%");
_builder.Append(value);
_builder.Append("%'");
}
}
else
{
_builder.Append("('%' + ");
_visitor.Visit(m.Arguments[0]);
_builder.Append(" + '%')");
}
return(m);
}
/// <summary>
/// 访问 EndWidth 方法
/// </summary>
/// <param name="m">方法表达式</param>
protected override Expression VisitEndsWith(MethodCallExpression m)
{
_visitor.Visit(m.Object);
if (this.NotOperands != null && this.NotOperands.Contains(m))
{
_builder.Append(" NOT");
}
_builder.Append(" LIKE ");
if (m.Arguments[0].CanEvaluate())
{
ColumnAttribute column = null;
bool isUnicode = SqlServerUtils.IsUnicode(_visitedMark.Current, out column);
string value = _constor.GetSqlValue(m.Arguments[0].Evaluate().Value, _builder.TranslateContext, column);
if (!_builder.Parameterized && value != null)
{
value = value.TrimStart('N').Trim('\'');
}
if (_builder.Parameterized)
{
_builder.Append("('%' + ");
_builder.Append(value);
_builder.Append(')');
}
else
{
if (isUnicode)
{
_builder.Append('N');
}
_builder.Append("'%");
_builder.Append(value);
_builder.Append("'");
}
}
else
{
_builder.Append("('%' + ");
_visitor.Visit(m.Arguments[0]);
_builder.Append(')');
}
return(m);
}
/// <summary>
/// 是否日期+时间类型
/// </summary>
/// <param name="dbType">DbType属性</param>
/// <returns></returns>
public static bool IsDateTime(object dbType)
{
if (dbType == null)
{
return(false);
}
else if (dbType is DbType)
{
return(((DbType)dbType) == System.Data.DbType.DateTime);
}
else if (dbType is SqlDbType)
{
return(((SqlDbType)dbType) == SqlDbType.DateTime);
}
else
{
return(SqlServerUtils.ThrowException(dbType));
}
}
/// <summary>
/// 检查指定的数据类型是否为 Unicode
/// </summary>
/// <param name="dbType">数据类型 <see cref="System.Data.DbType"/> </param>
/// <returns></returns>
public static bool IsUnicode(object dbType)
{
if (dbType == null)
{
return(true);
}
else if (dbType is DbType)
{
return(((DbType)dbType) == System.Data.DbType.String || ((DbType)dbType) == System.Data.DbType.StringFixedLength);
}
else if (dbType is SqlDbType)
{
return(((SqlDbType)dbType) == SqlDbType.NVarChar || ((SqlDbType)dbType) == SqlDbType.NChar || ((SqlDbType)dbType) == SqlDbType.NText);
}
else
{
return(SqlServerUtils.ThrowException(dbType));
}
}
/// <summary>
/// 设置命令参数对象的 DbType属性
/// </summary>
/// <param name="parameter">命令参数对象</param>
/// <param name="dbType">DbType属性</param>
public static void DbType(this SqlParameter parameter, object dbType)
{
if (dbType != null)
{
if (dbType is DbType)
{
parameter.DbType = (DbType)dbType;
}
else if (dbType is SqlDbType)
{
parameter.SqlDbType = (SqlDbType)dbType;
}
else
{
SqlServerUtils.ThrowException(dbType);
}
}
else if (parameter.Value != null && parameter.Value is DateTime && dbType == null)
{
// 如果 DateTime 没有指定 DbType，则需要转为 DateTime2才能保持原有的精度
parameter.DbType = System.Data.DbType.DateTime2;
}
}
/// <summary>
/// 检查字段或属性成员声明的 DbType 是否为 Unicode 数据类型
/// </summary>
/// <param name="m">将要检查的字段或属性成员</param>
/// <param name="column">字段或属性成员显示声明的列特性</param>
/// <returns></returns>
public static bool IsUnicode(MemberVisitedStack.VisitedMember m, out ColumnAttribute column)
{
column = m != null?TypeUtils.GetColumnAttribute(m.Member, m.ReflectedType) : null;
return(SqlServerUtils.IsUnicode(column == null ? null : column.DbType));
}
/// <summary>
/// 检查字段或属性成员声明的 DbType 是否为 Unicode 数据类型
/// </summary>
/// <param name="m">将要检查的字段或属性成员</param>
/// <returns></returns>
public static bool IsUnicode(MemberVisitedStack.VisitedMember m)
{
ColumnAttribute column = null;
return(SqlServerUtils.IsUnicode(m, out column));
}
/// <summary>
/// 访问 ToString 方法
/// </summary>
protected override Expression VisitToStringImpl(Expression node)
{
// => a.ID.ToString()
// 字符串不进行转换
if (node == null || node.Type == typeof(string))
{
return(_visitor.Visit(node));
}
ColumnAttribute column = null;
bool isUnicode = SqlServerUtils.IsUnicode(_visitedMark.Current, out column);
string native = isUnicode ? "NVARCHAR" : "VARCHAR";
// 其它类型转字符串
bool isDate = node.Type == typeof(DateTime) ||
node.Type == typeof(DateTime?) ||
node.Type == typeof(TimeSpan) ||
node.Type == typeof(TimeSpan?) ||
node.Type == typeof(DateTimeOffset) ||
node.Type == typeof(DateTimeOffset?);
if (isDate)
{
native = string.Format("{0}(64)", native);
_builder.Append("CONVERT(");
_builder.Append(native);
_builder.Append(",");
_visitor.Visit(node);
_builder.Append(",121)");
}
else if (node.Type == typeof(byte[]))
{
native = string.Format("{0}(max)", native);
_builder.Append("CONVERT(");
_builder.Append(native);
_builder.Append(",");
_visitor.Visit(node);
_builder.Append(",1)");
}
else if (node.Type == typeof(Guid))
{
native = string.Format("{0}(64)", native);
_builder.Append("CAST(");
_visitor.Visit(node);
_builder.Append(" AS ");
_builder.Append(native);
_builder.Append(')');
}
else
{
if (column != null && column.Size > 0)
{
native = string.Format("{0}({1})", native, column.Size);
}
else if (column != null && column.Size == -1)
{
native = string.Format("{0}(max)", native);
}
else
{
native = string.Format("{0}(max)", native);
}
_builder.Append("CAST(");
_visitor.Visit(node);
_builder.Append(" AS ");
_builder.Append(native);
_builder.Append(')');
}
return(node);
}