What MySQL Output is
Not a file format at all. It is what the MySQL command line prints when you run a query: a box drawn with plus signs, dashes and pipes, with a line underneath saying how many rows were in the set.
Anyone who has run a query in a terminal and wants the answer in a spreadsheet.
What XML is
XML marks up data with nested named tags and optional attributes. It is verbose, strict about being well-formed, and can carry a schema that says what shape a document must have.
Enterprise integrations, government data feeds, RSS, SOAP services and older document formats.
What changes when you convert MySQL Output to XML
The rules and the trailing row count are dropped and the pipes become column boundaries. MySQL prints an unset value as the four characters NULL, which arrives here as an empty cell, because that is what NULL means and because a literal string of NULL in a spreadsheet is worse than a blank. Paste it as CSV instead and every row becomes one column full of pipes, which is why this is its own format.
Each row becomes an element with one child per column. Header names are rewritten where they have to be, because an XML tag cannot start with a digit or contain a space, so a column called 2024 Sales becomes _2024_Sales.
What carries over from MySQL Output to XML
MySQL records 3 things about a table that XML has no way to hold.
MySQL distinguishes a number from the text of a number; XML does not, so every value arrives as text and has to be re-parsed by whatever reads it next.
An empty cell and a missing one are the same thing in XML, so a null and an empty string in the MySQL both come out blank and can no longer be told apart.
XML has no header row. The column names are repeated as keys on every record instead, which is why the result is bigger on disk than the table it came from.
The identifier 007 comes out of the XML as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a XML file goes wrong.
The quotes around Jonah "Jo" Pryce are written as the HTML entity " in the XML.