CREATE TABLE table_train_237 ("id" NUMBER, "fasting_c_peptide" FLOAT, "fasting_plasma_glucose" NUMBER, "smoking" BOOLEAN, "body_mass_index_bmi" FLOAT, "serum_25_oh_d_levels" NUMBER, "NOUSE" FLOAT)

serum 25 ( oh ) d levels < 20 ng / ml.
SELECT * FROM table_train_237 WHERE serum_25_oh_d_levels < 20
SELECT * FROM "table_train_237" WHERE "serum_25_oh_d_levels" < 20