This article describes features or functionality that are only compatible with Fusion 4.x through Fusion 5.3.5.
The JDBC connector is configured with the SQL statement used to retrieve a resultset from the database. Each row in the result set is treated as a Solr document. This statement is specified as the value of the required property sql_select_statement. The column names will be used as Solr document field names; use the SQL “AS” keyword to rename column names as needed. Column and table names should be treated as if they are case-insensitive, even though some databases allow use of mixed case names. All Solr documents must have a unique key, which is the Fusion “id” field. Therefore, the results set must contain a column “id” which can be used as a unique key for the resulting document. 
SELECT customer_id AS id, * from customers

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Delta queries

Delta queries provide incremental updates to the contents of a collection by indexing only those records in the database which have been changed since the database was last indexed by this connector. The SQL statement is specified as the value of the property delta_sql_query. Delta queries select only primary key values, therefore, the query must use the primary key and it must also have a “WHERE” clause which specifies a “last_modified” condition as follows: 
SELECT customer_id AS id from customers WHERE last_modified > $
The dollar-sign character ’$’ is required; it holds the last successful import time from the database.

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Nested queries

Nested queries are used to index information which is stored in the database across a series of tables where the is a one-to-many or many-to-many relationship between them. This statement is specified as the value of the property nested_queries. A nested query is used in conjunction with the SQL query specified by the sql_select_statement statement. The dollar-sign character ’$’ specifies the primary key in the resultset retrieved by the sql_select_statement statement. The following example shows the pair of query, nested query statements used to index list of tags assigned to documents: 
SELECT id FROM document
SELECT tag FROM tag INNER JOIN document_tag ON document_tag.tag_id=tag.id WHERE document_tag.doc_id=$