As addition to Mike's solution, I have used the CHARINDEX method which checks for a comma -
MS Learn | CHARINDEX (Transact-SQL)[
^]
SELECT TOP 5
BINANCE.symbol,
BINANCE.bidPrice AS BINANCE,
MEXC.bidPrice AS MEXC,
WAZIRX.bidPrice AS WAZIRX,
IIF(BINANCE.bidPrice > MEXC.bidPrice, 'BINANCE',
IIF(MEXC.bidPrice > WAZIRX.bidPrice, 'MEXC', 'WAZIRX')) AS GetMax
FROM
BINANCE,
MEXC,
WAZIRX
WHERE
CHARINDEX(',', BINANCE.bidPrice) > 0
OR CHARINDEX(',', MEXC.bidPrice) > 0
OR CHARINDEX(',', WAZIRX.bidPrice) > 0
ORDER BY
GetMax;