CREATE TABLE table_23097 ("Districts of Bihar" TEXT, "Total Population 2001" FLOAT, "Male Population 2001" FLOAT, "Female Population 2001" FLOAT, "Growth Rate 1981-91" TEXT, "Growth Rate 1991-01" TEXT, "Sex Ratio \\u2021 1991" FLOAT, "Sex Ratio \\u2021 2001" FLOAT, "Population density \\u2020 1991" FLOAT, "Population density \\u2020 2001" FLOAT)

What districts of Bihar have a sex ratio in 1991 of 864?
SELECT "Districts of Bihar" FROM table_23097 WHERE "Sex Ratio \u2021 1991" = '864'
SELECT "Districts of Bihar" FROM "table_23097" WHERE "Sex Ratio \u2021 1991" = '864'