When using the FOR XML clause in a query in SQL Server, we can generate an XML document either with or without an inline schema.
To generate it with an inline XSD schema simply include the XMLSCHEMA argument. We can alternatively include the namespace if we want to specify a particular namespace.
At the time of writing, the XMLSCHEMA argument is only available when in either AUTO or RAW mode.
In SQL Server, when we use FOR XML to return query results in an XML document, the resulting XML document is returned as a string by default. However, we can change this so that it’s returned in the xml data type.
To do this, all we need to do is append our query with the TYPE directive.
If we ever need to assign repeating sequence numbers to a result set in SQL Server, we can use a sequence object with the appropriate arguments.
In particular, we can use the CYCLE argument to specify that the sequence will cycle through the range of numbers. In other words, once it reaches the end of the sequence, it starts again, and will continue to reiterate every time it completes the sequence.
If you’re getting error msg 237 that reads There is insufficient result space to convert a money value to int, it’s because you’re trying to convert a money value to an integer but the number’s too big to fit into an integer.
To fix this issue, make sure you convert the value to a data type that can handle the size of the number that you’re trying to convert.
Continue readingIf you’re getting an error that reads something like “Cannot DROP SEQUENCE ‘Sequence2’ because it is being referenced by object ‘DF__Dogs__DogId__6C190EBB’“, it could be because you’re trying to drop a sequence object that’s referenced by a DEFAULT constraint.
Sequences that are referenced by a DEFAULT constraint can’t be dropped until the DEFAULT constraint is dropped.
Therefore, to fix this issue, drop the DEFAULT constraint first.
By default, SQL Server sets its own minimum and maximum values for sequence objects based on the data type of the sequence object. Assuming we don’t set the data type for the sequence, these min/max values are based on the bigint data type (because that’s the default data type for sequence objects in SQL Server).
However, we can also set our own minimum and maximum values for our sequences. We can do this either explicitly (by setting the MAXVALUE and MINVALUE properties) or implicitly (by setting the data type).
If you’re getting error msg 6825 that reads “ELEMENTS option is only allowed in RAW, AUTO, and PATH modes of FOR XML“, it’s probably because you’re trying to use the ELEMENTS directive while using EXPLICIT mode of the FOR XML clause.
As the message alludes to, this option is not available when using the EXPLICIT mode (it’s only allowed with the RAW, AUTO, and PATH modes).
However, SQL Server does provide us with an equivalent that provides the same result. When using EXPLICIT mode, we can use the ELEMENT directive instead. We apply this to the column names, instead of the end of the query. We can alternatively use the ELEMENTXSINIL directive to ensure that elements are generated even if the column contains a NULL value.
If you’re getting an error that reads “Argument ‘AS’ cannot be used in an ALTER SEQUENCE statement.” in SQL Server, it’s probably because you’re trying to change the data type of a sequence object.
We can’t actually change the data type of a sequence object, so this error is to be expected.
If you need to change the data type of a sequence object, you’ll need to drop the sequence and recreate it with the correct data type.
Continue readingIn SQL Server, the FOR XML clause allows us to return the results of a query as an XML document.
When we use this clause, we have various options for how we want to shape the resulting XML document.
Below is an explanation of how the FOR XML clause works, including the basic options we have when using it.
SQL Server’s ISDATE() function checks whether or not an expression is a valid date. However, you may be aware that this function doesn’t work on datetime2 values. On datetime2 values it returns 0, which means it’s not a valid date, even when the value is a valid date.
This is obviously not ideal, because the datetime2 type is a valid date type. Microsoft even recommends that we use datetime2 instead of datetime for our dates, as it aligns with the SQL Standard and it provides more fractional seconds precision.
Anyway, below are three options we can use to check whether a datetime2 value is a valid date.
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