What was the rating/share for 18-49 for the episode that had 5.90 million viewers? 
CREATE TABLE table_23730973_5 (rating VARCHAR, viewers__millions_ VARCHAR)
SELECT rating / NULLIF(SHARE(18 - 49), 0) FROM table_23730973_5 WHERE viewers__millions_ = "5.90"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_23730973_5 (rating VARCHAR, viewers__millions_ VARCHAR) Question: What was the rating/share for 18-49 for the episode that had 5.90 million viewers?  [/INST] SELECT rating / NULLIF(SHARE(18 - 49), 0) FROM table_23730973_5 WHERE viewers__millions_ = "5.90" </s>