Partial comparison from the beginning of a character field

Sometimes you need to make a partial comparison that matches the beginning of a characters field, instead of matching the entire field. For example, you want to select a company named “Acme”, but you do not know whether the full name is “Acme Company”, “Acme, Inc.”, or even “Acme”.

In SQL, you apply a partial comparison predicate with the LIKE operator in the WHERE clause. The following SQL statement applies the predicate LIKE "Acme%" to values in the name column of the companies table. The percent sign (%) is an SQL wildcard symbol that matches zero or more characters.

SELECT * from companies
  WHERE name LIKE "Acme%";

The query result contains companies with names that begin with “Acme”.

With the query builder APIs, you apply partial comparison predicates that match from the beginnings of character fields by using the startsWith method on the query object. Test the use of the startsWith method in a realistic environment. Using the startsWith method as the most restrictive predicate on a query can cause a delay on the user interface.

The following Gosu code applies the startsWith predicate method to values in the Name field on Company entity instances.

uses gw.api.database.Query

// Query the Company instances for a specific company. 
var queryCompany = Query.make(Company)
queryCompany.startsWith(Company#Name, "Acme", false)

// Fetch the data with a for loop.
var result = queryCompany.select()
for (company in result) {
  print (company.Name)
}

The sample code prints the names of companies that begin with “Acme”.

See also

• Case-insensitive partial comparisons of a character field
• Linguistic search and sort