What is the longest length of mandatory secondary school?
CREATE TABLE table_1831309_1 (length_of_mandatory_secondary_school INTEGER)
SELECT MAX(length_of_mandatory_secondary_school) FROM table_1831309_1
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_1831309_1 (length_of_mandatory_secondary_school INTEGER) Question: What is the longest length of mandatory secondary school? [/INST] SELECT MAX(length_of_mandatory_secondary_school) FROM table_1831309_1 </s>