A DAX DATATABLE expression that defines a table inline in a Power BI model.
Who uses it
Power BI report authors.
Writing DAX
All columns are declared as STRING. Change the type declarations by hand if you need numeric columns.
What is DAX?
What it can hold
DAX is source code. A DATATABLE call declares each column's type up front, so every column needs one decided for it. A machine can read the table back out of it without guessing, which is what makes it safe to convert into and out of.
It keeps
- Types. A number stays a number and a boolean stays a boolean, so whatever reads the file next does not have to guess from how a value looks.
- A header that is marked as one, rather than being the first row by convention.
It cannot express
- Nesting. Cells are flat, so structured values have to be flattened into extra columns or written into one cell as text.
- A line break inside a cell. One would end the row, so it has to be replaced before writing.
- Any formatting. Bold, colour, column widths and merged cells have nowhere to go.
- A partial read. The document has to be complete to mean anything, so a truncated file yields nothing and a large one has to be held in memory whole.
What it looks like
staff =
DATATABLE(
"id", STRING,
"name", STRING,
"role", STRING,
"started", STRING,
"hours", STRING
{
{"007", "Halima Yusuf", "Analyst, data", "2024-03-15", "38.5"},
{"012", "Jonah \"Jo\" Pryce", "Engineer", "2025-11-02", ""},
{"104", "Wei Chen", "Manager", "2023-06-30", "40"}
}
)Questions
How do I open DAX files?
DAX is written by Tablizer rather than read by it. Open the file in whichever tool the format belongs to.
Is DAX a good format for sharing data?
It depends who is receiving it. Power BI report authors. If the recipient is outside that group, a plain CSV travels further than anything else.