What SQL is
SQL here means the statements that move a table into a database: INSERT INTO with a VALUES list, and optionally the CREATE TABLE that defines the columns.
Anyone seeding a database, moving a spreadsheet into an application, or writing a migration.
What JSON Lines is
JSON Lines is one complete JSON object per line, with no enclosing array and no commas between records. The file is not valid JSON as a whole, and that is the point.
Log pipelines, machine learning datasets and anything that appends records or reads them in a stream.
What changes when you convert SQL to JSON Lines
Column names come from the INSERT column list, or from a CREATE TABLE if one is present. Quoted strings are unquoted, doubled quotes are collapsed, and NULL becomes an empty cell.
Every row becomes one line. You can append to the file forever without rewriting it, and a reader can process it a line at a time without holding the whole thing in memory.
What carries over from SQL to JSON Lines
SQL records 2 things about a table that JSON Lines has no way to hold.
A line break inside a cell ends the row in JSON Lines, so line breaks are replaced rather than carried through.
JSON Lines 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.
Both formats record types, so numbers, booleans and nulls survive as themselves rather than as text.
The identifier 007 comes out of the JSON Lines 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 JSON Lines file goes wrong.
The quotes around Jonah "Jo" Pryce are escaped with a backslash in the JSON Lines.