DBMS

Database Management Systems

Understanding the Difference Between SCALE(), MIN_SCALE() and TRIM_SCALE() in PostgreSQL

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Anyone who looks at PostgreSQL’s list of mathematical functions will notice that there are some functions that have “scale” in their name. In particular, scale(), min_scale(), and trim_scale().

While these functions all have a similar name, they each have a different purpose. That said, they’re all related to the scale of the given number. The scale is the number of digits to the right of the decimal point in a number. For example, the number 1.95 has a scale of 2, and 1.958 has a scale of 3.

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Fix Error 1987 “Cannot alter nonclustered index … because its clustered index is disabled” in SQL Server

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If you’re getting SQL Server error 1987 that reads something like “Cannot alter nonclustered index ‘UQ_Employees_Email’ on table ‘Employees’ because its clustered index is disabled“, it’s probably because you’re trying to rebuild a nonclustered index when the clustered index for the table is disabled.

To fix this issue, either enable/rebuild the table’s clustered index first, then try again, or enable all indexes at once.

The clustered index will typically be the primary key index (unless you’ve specified another clustered index for the table).

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What is a Synonym in SQL Server?

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In SQL Server, a synonym is a database object that provides an alternative name for another database object, such as a table, view, stored procedure, or function. Synonyms act as aliases, allowing us to reference objects using different names without changing the underlying object itself.

The underlying object that the synonym references is typically referred to the base object. Either way, the synonym allows us to reference the base object without actually referring to its name (we refer to the synonym’s name instead).

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Fix Error 4512 “Cannot schema bind view” in SQL Server Due to “two-part format” Issue

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If you’re getting an error that reads something like “Cannot schema bind view ‘vEmployees’ because name ‘Employees’ is invalid for schema binding. Names must be in two-part format and an object cannot reference itself” it could be that you’re trying to create a schema bound view, but you’re not using a two-part format for names (such as the table names within the view).

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2 Ways of Creating a Composite Type in PostgreSQL

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In PostgreSQL, a composite type is a data type that represents the structure of a row or record. It’s basically a list of field names and their data types.

We can use composite types in many of the same ways we can use simple types, such as in table columns.

Below are two ways of creating composite types in PostgreSQL.

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How to Create an Array Column in PostgreSQL

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PostgreSQL allows us to create arrays and store them in a database column. When we do this, we can use various array related tools to retrieve data from such arrays, as well as manipulate the data within them.

We do need to define the column as an array column though. If we don’t do this, we will likely run into trouble when we want to retrieve data from the array. For example, we can’t just store an array as the text type and then expect to be able to use subscripts to refer to its individual elements.

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Fix Error “Drop table operation failed on table … because it is not a supported operation on system-versioned temporal tables” in SQL Server

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If you’re getting an error that reads something like “Drop table operation failed on table ‘db.dbo.TableName’ because it is not a supported operation on system-versioned temporal tables” in SQL Server, it’s probably because you’re trying to drop a temporal table that still uses system-versioning.

In SQL Server, if a table is defined as a temporal table, we can’t drop it while it’s using system-versioning.

If you really want to drop the table, turn off system-versioning first, then try again.

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