bqb

A query builder for BigQuery.

Why use this?

The most common way to write a BigQuery query is to combine a query string with a []bigquery.QueryParameter slice which contains the query parameter values. But that has some big downsides:

• []bigquery.QueryParameter gets out of sync with the parameters in the query string. For example, you might have a query param in your query string that isn’t in your []bigquery.QueryParameter.
• No type checking for []bigquery.QueryParameter values.
• Without a query builder, dynamic queries require error-prone string manipulation.

Examples

Basic

To create this query:

SELECT id, name, age,
FROM my_table
WHERE age > 50
  AND name = 'bob'

Write this code:

query, err := Build(
    &client,
    Query(
        Select("id", "name", "age"),
        From("my_table"),
        Where("age > 50"),
        Where("name = 'bob'"),
    ),
)

Parameterized queries

BigQuery supports parameterized queries. Parameter names have an @ prefix in the query (e.g. @age) and must have matching bigquery.QueryParameter object.

To create this query:

SELECT id, name, age,
FROM my_table
WHERE age > @age
  AND name = @name

Write this code:

query, err := Build(
    &client,
    Query(
        Select("id", "name", "age"),
        From("my_table"),
        Where("age > @age"),
        Where("name = @name"),
    ),
    ParamInt("age", 50),
    ParamStr("name", "bob"),
)

The Build function will automatically populate query.Parameters and check that all parameters in the query have been specified (e.g. using ParamInt).