常用语句：
获取上年年份：SELECT TO_CHAR (current_date, 'YYYY')-1 "to char" FROM DUMMY
SAP HANA 常用函数：
数据类型转换函数(Data Type Conversion Functions ):
CAST 语法：CAST (表达式AS 数据类型) SELECT CAST (7 AS VARCHAR)"cast" FROM DUMMY; 结果----->7 把7转换成字符串。 把表达式转换成目标数据类型。
数据类型：TINYINT | SMALLINT | INTEGER | BIGINT | DECIMAL | SMALLDECIMAL | REAL | DOUBLE | ALPHANUM | VARCHAR | NVARCHAR | DAYDATE | DATE | TIME | SECONDDATE | TIMESTAMP
TO_ALPHANUM 语法： TO_ALPHANUM (value) SELECT TO_ALPHANUM ('10')"to alphanum" FROM DUMMY; 结果----> 10 把value转换成字母数字类型
TO_BIGINT 语法：TO_BIGINT (value) SELECT TO_BIGINT ('10')"to bigint" FROM DUMMY; 结果--------->10 把value转换成二进制类型
TO_BLOB 语法：
TO_CHAR SELECT TO_CHAR (TO_DATE('2009-12-31'), 'YYYY/MM/DD') "to char" FROM DUMMY;
TO_CLOB
TO_DATE SELECT TO_DATE('2010-01-12', 'YYYY-MM-DD') "to date" FROM DUMMY;
TO_DATS
TO_DECIMAL
TO_DOUBLE
TO_INT
TO_INTEGER
TO_NCHAR
TO_NCLOB
TO_NVARCHAR
TO_REAL
TO_SECONDDATE
TO_SMALLDECIMAL
TO_SMALLINT
TO_TIME
TO_TIMESTAMP
TO_TINYINT
TO_VARCHAR
日期/时间函数(DateTime Functions ):
ADD_DAYS
ADD_MONTHS
ADD_SECONDS
ADD_YEARS
CURRENT_DATE
CURRENT_TIME
CURRENT_TIMESTAMP
CURRENT_UTCDATE
CURRENT_UTCTIME
CURRENT_UTCTIMESTAMP
DAYNAME
DAYOFMONTH
DAYOFYEAR
DAYS_BETWEEN
EXTRACT
HOUR
ISOWEEK
LAST_DAY
LOCALTOUTC
MINUTE
MONTH
MONTHNAME
NEXT_DAY
NOW
QUARTER
SECOND
SECONDS_BETWEEN
UTCTOLOCAL
WEEK
WEEKDAY
YEAR
数字类型相关函数:(Number Functions)
ABS
ACOS
ASIN
ATAN
ATAN2
BINTOHEX
BITAND
CEIL
COS
COSH
COT
EXP
FLOOR
GREATEST
HEXTOBIN
LEAST
LN
LOG
MOD
POWER
ROUND
SIGN
SIN
SINH
SQRT
TAN
TANH
UMINUS
字符串相关函数：(String Functions)
ASCII SELECT ASCII('Ant')"ascii" FROM DUMMY; 结果 ----> 65
CHAR SELECT CHAR (65) || CHAR (110) || CHAR (116)"character" FROM DUMMY;
CONCAT SELECT CONCAT ('C','at') "concat" FROM DUMMY; 结果---->Cat CONCAT (str1, str2) 把字符串str1和str2拼接起来
LCASE SELECT LCASE ('TesT')"lcase" FROM DUMMY; 结果------>test 把字符串全部转换成小写
LEFT SELECT LEFT ('Hello', 3)"left" FROM DUMMY; 结果-------->Hel
LENGTH SELECT LENGTH ('length in char')"length" FROM DUMMY; 结果---->14 获取字符串的长度
LOCATE SELECT LOCATE ('length in char','char') "locate" FROM DUMMY; 结果--->11 获取子字符串出现第一次的位置
LOWER SELECT LOWER ('AnT')"lower" FROM DUMMY; 结果----->ant 把字符串转成小写
NCHAR
REPLACE
RIGHT
RPAD
RTRIM
SUBSTR_AFTER
SUBSTR_BEFORE
SUBSTRING
TRIM
UCASE
UNICODE
UPPER
其他函数:
COALESCE
CURRENT_CONNECTION
CURRENT_SCHEMA
CURRENT_USER
GROUPING_ID
IFNULL
MAP
NULLIF
SESSION_CONTEXT
SESSION_USER
SYSUUID