When I use SQL, Sigma replaces hyphens and underscores in my column titles

SELECT column1 AS “FUND-INVEST”,
column2 AS “RETURNS 3MONTH”
FROM …
but for output columns I get
FUND INVEST (without the hyphen)
and
RETURNS 3 MONTH (with extra space between 3 and MONTH)

Like many other BI tools, Sigma will take a column name “FUND-INVEST” or “FUND_INVEST” and will display is as “FUND INVEST”, when it initially generates the worksheet. You can rename that column in the worksheet.