If you’re getting an error that reads something like “START value (101) cannot be greater than MAXVALUE (100)” in PostgreSQL when you’re trying to create a sequence, it’s probably because your sequence’s maximum possible value is lower than the start value.
To fix this issue, change either the start value or maximum value so that the maximum value is greater than the start value.
Continue readingWhen 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.
If you’re getting an error in PostgreSQL that reads something like “cannot insert into column” with detail that explains that the “…is an identity column defined as GENERATED ALWAYS“, it’s probably because you’re trying to insert your own value into an identity column that was created with the GENERATED ALWAYS option, but you’re not explicitly overriding the column from auto generating its own value.
To fix this issue, use OVERRIDING SYSTEM VALUE when inserting the value.
If you’re getting an error that reads something like “ERROR 1050 (42S01) at line 22: Table ‘Pets’ already exists” when trying to create a table in MariaDB, it’s most likely because there’s already a table in the database with the same name.
To fix this issue, either change the name of the table you’re trying to create, or check the existing table to see if it’s the one you actually need.
Continue readingIn MySQL, we can use the SHOW CREATE TABLE statement to generate a CREATE TABLE script for existing tables. This enables us to recreate the table without having to manually type out the table’s definition.
If you’re getting an error that reads something like “nextval: reached maximum value of sequence “sequence1” (3)” in PostgreSQL, it’s probably because you’re trying to generate a new value from a sequence, but the sequence has already reached its maximum value.
We have quite a few options when it comes to dealing with this issue.
Continue readingIf you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZMPOP or BZMPOP commands in Redis, it’s because you’re passing a key with the wrong data type.
To fix this issue, make sure you pass a sorted set to these commands.
Continue readingIn 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 you’re getting an error that reads something like ‘currval of sequence “sequence1” is not yet defined in this session‘ when calling the currval() function in PostgreSQL, it’s probably because nextval() hasn’t yet been called for that sequence in the current session.
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.