In the Translator, you can read data from a database by either calling stored procedures or using conn:query{} to execute ad hoc SQL SELECT statements on a database. See Writing SQL Statements.
local R = conn:query{sql='SELECT * FROM Patients WHERE LastName=' ..conn:quote(lastName)}
The conn:query{} method will execute SELECT statements when you make any script alterations or changes to the sample data. It assumes that the SELECT statements do not alter the state of the database and can be safely run to power the Translator’s annotation and auto-completion.
The function returns the database query result sets. It can also throw a Lua error if a database error occurs. The error thrown is a table with two values:
message: a string with the description of the error.
code: an integer error code returned by the database.
pcall() can be used to perform a protected call, capturing any returned database errors allowing you to appropriately handle errors according to your needs. In this example, we are using pcall to catch and log the error message.
function getPatient(conn, lastName)
-- Query patient from the database
local R = conn:query{sql='SELECT * FROM Patients WHERE LastName=' ..conn:quote(lastName)}
end
function main(Data)
-- Connect to the database
local conn = db.connect{api = db.SQLITE, name = 'demo.db'}
local lastName = "O'Reilly"
local Success, Err = pcall(getPatient, conn, lastName)
if (not Success) then
-- Handle error
iguana.log(Err.message)
end
end
Using the Annotations you can view database query result tables easily:
