Relation:update
Updates a column to the current relation based on an expression and a condition
Description
update name = expression where condition
Parameters
- name: must be a valid name.
- expression: any expression.
- condition: any expression that evaluates to 1 or 0.
Examples
Using the sample relation films.csv
read "films.csv"
update film = upper(film) where director == "Godard"
print
| film | director | year |
|---|---|---|
| A BOUT DE SOUFFLE | Godard | 1960 |
| Tirez sur le pianiste | Truffaut | 1960 |
| Cléo de 5 à 7 | Varda | 1962 |
| Jules et Jim | Truffaut | 1962 |
| PIERROT LE FOU | Godard | 1965 |
| WEEK-END | Godard | 1967 |
| Die verlorene Ehre der Katharina Blum | von Trotta | 1975 |
| Der starke Ferdinand | Kluge | 1976 |
| Sans toi ni loi | Varda | 1985 |
Comments
The expression can use any column of the current row and any global variable. It has not access to the other rows of the relation.
Variables can be numbers or text, it depends on the operators used in the expression. See expressions
The number of rows and the order stays the same.