build_sql_in: Build a SQL IN statement.
In TheFridayInstitute/fimoodler: Data Export for Friday Institute Moodle courses

Description Usage Arguments Details Value Examples

Returns SQL IN statement as a string. Supports multi-variable value matching with tuples.

1	build_sql_in(var_names, values)

`var_names`	A character vector specifying the names of the database columns to which the condition applies. If `values` is a vector, `names` should have a length of 1. If `values` is a data frame, `names` should have a length of `ncol(values)`.
`values`	A vector or data frame containing values to match on. Factors will be converted to strings. Rows of a data frame are treated as tuples.

Concatenates values in a vector and returns them in a SQL conditional format. This is necessary since Friday Institute researchers are given read-only access to the database. Otherwise, you could use dplyr join commands with copy=TRUE, which would create a temporary table in the database, so the database can handle the calculations. If this breaks, you can always pull the entire table and do subsetting locally, but that's obviously expensive.

A string of format "name IN (value1, value2, ...)" for vector inputs and "(name1, name2) IN ((name1value1, name2value1), ...)" for data frames.

## Not run: 
courseids <- c(1, 2, 3)
build_sql_in("courseid", courseids)

# tuple
tuple <- tribble(
  ~courseid, ~userid,
  1,         1,
  1,         2,
  2,         3,
  2,         4
)
build_sql_in(c("courseid", "userid"), tuple)

## End(Not run)