CREATE TABLE table_57550 ("Player" CLOB, "Position" CLOB, "School" CLOB, "Hometown" CLOB, "MLB Draft" CLOB)

Which position has a School of green valley high school?
SELECT "Position" FROM table_57550 WHERE "School" = 'green valley high school'
SELECT "Position" FROM "table_57550" WHERE "School" = 'green valley high school'