If you find yourself running a lot of ad-hoc queries that start with SELECT * FROM, you might be interested in this interesting feature of DuckDB.
DuckDB allows us to start queries with the FROM clause. When we do this, DuckDB will return all columns without us needing to specify SELECT *.
This article demonstrates how to output your DuckDB query results in LaTeX table format, which can be useful when preparing academic papers, technical documents, or any content that needs to be typeset using LaTeX.
Continue readingDuckDB’s CLI allows you to output query results in different formats, including NDJSON (Newline Delimited JSON).
NDJSON is similar to JSON, except that with NDJSON, each line contains its own self-contained JSON document.
This article shows you how to check your current output mode, and then change it to NDJSON.
Continue readingWhen using DuckDB’s command line interface (CLI), we can use the .mode command to change how query results are formatted. For example, we can output query results as a table, in CSV format, or even JSON. Another option is to output it in “line” mode, which outputs the query results vertically, as opposed to horizontally across the screen.
This article demonstrates how to enable vertical query output in the DuckDB CLI with line mode.
DuckDB’s CLI provides a convenient way to generate INSERT statements from query results. This can be particularly useful for data migration, creating test data, or backing up specific data subsets. Here’s how to do it.
DuckDB’s command line interface (CLI) provides a convenient .mode csv command that allows you to output all query results directly in CSV format. This approach differs from the COPY statement as it affects the output format of all subsequent queries until changed.
The article takes a quick look at CSV mode in the DuckDB CLI.
Continue readingIf you’re getting an error that reads something like “1052 (23000): Column ‘name’ in field list is ambiguous” in MySQL, it looks like you could be referencing a column name in a query without qualifying it with the table name.
This can happen when you perform a join between tables that use the same name for one or more columns.
To fix this issue, be sure to qualify column names with the table names when performing joins across tables.
Continue readingIf you’re getting an error that reads something like “ERROR 1066 (42000): Not unique table/alias: ‘d’” in MySQL, it could be that you’re trying to assign a duplicate alias to a table. Or it could be that you’re doing a self-join without assigning table aliases.
Table names and aliases must be unique when doing queries in MySQL.
The error can also happen if you use HANDLER to open a table, but then try to open it again before closing it.
To fix this issue, be sure to use unique table aliases in your query. And if you’re using HANDLER, either close the table or continue working with it (without trying to open it again).
If you’re trying to use a common table expression (CTE) that produces XML in SQL Server, but you’re getting error 4121, which reads something like “Cannot find either column “EmployeeData” or the user-defined function or aggregate “EmployeeData.query”, or the name is ambiguous” it might be that you’re trying to query the XML in the outer query, but your CTE isn’t outputting the XML as an actual xml type.
The FOR XML result must be an xml type in order to process the result on the server.
To fix this issue, make sure the CTE outputs the result using the xml data type.
Continue readingIf you’re getting MySQL error 1109 which reads something like “1109 (42S02): Unknown table ‘products’ in HANDLER” in MySQL, it appears that you’re trying to reference a table that’s not currently open when using MySQL’s HANDLER statement.
This can happen when you try to read from a table that you haven’t yet opened. It can also happen when you’ve assigned an alias to the table but you try to reference it without the alias. And it can happen if you try to close a table that isn’t actually open.
Continue reading