What is Concat_ws in hive?
CONCAT_WS( string delimiter, string str1, string str2… ) The CONCAT_WS function is similar to the CONCAT function. Here you can also provide the delimiter, which can be used in between the strings to concat. Example: CONCAT_WS(‘-‘,’hadoop’,’hive’) returns ‘hadoop-hive’
What will be the output of Concat_ws?
CONCAT_WS() function The separator specified in the first argument is added between two strings. The separator itself can be a string. If the separator is NULL the result is NULL.
What does Concat_ws do in SQL?
The CONCAT_WS() function joins the input strings into a single string. It separates those concatenated strings with the separator specified in the first argument. Note that the CONCAT_WS() requires at least two input strings. It means that if pass zero or one input string argument, the function will raise an error.
How do you concatenate null values in SQL?
Standard SQL requires that string concatenation involving a NULL generates a NULL output, but that is written using the || operation: SELECT a || b FROM SomeTable; The output will be null if either a or b or both contains a NULL. Using + to concatenate strings indicates that you are using a DBMS-specific extension.
What is the difference between concat and Concat_ws?
Both CONCAT() and CONCAT_WS() functions are used to concatenate two or more strings but the basic difference between them is that CONCAT_WS() function can do the concatenation along with a separator between strings, whereas in CONCAT() function there is no concept of the separator.
How do I convert a string to a date in Hive?
SELECT TO_DATE(from_unixtime(UNIX_TIMESTAMP(‘open_time’, ‘dd/MM/yyyy’))); But it returns NULL. Subsequently, my objectif is to do something like this : SELECT * FROM table_hive WHERE open_time BETWEEN ’29-MAR-17′ AND ’28-MAR-17′;
IS NOT NULL in MySQL?
Here is an example of how to use the MySQL IS NOT NULL condition in a SELECT statement: SELECT * FROM contacts WHERE last_name IS NOT NULL; This MySQL IS NOT NULL example will return all records from the contacts table where the last_name does not contain a null value.
What is || in SQL query?
Concatenation Operator. ANSI SQL defines a concatenation operator (||), which joins two distinct strings into one string value.
Is null and coalesce SQL?
The SQL Coalesce and IsNull functions are used to handle NULL values. During the expression evaluation process the NULL values are replaced with the user-defined value. The SQL Coalesce function evaluates the arguments in order and always returns first non-null value from the defined argument list.
What is Group_concat in MySQL?
The GROUP_CONCAT() function in MySQL is used to concatenate data from multiple rows into one field. This is an aggregate (GROUP BY) function which returns a String value, if the group contains at least one non-NULL value. Otherwise, it returns NULL.
How does concat _ WS handle null values in SQL?
If CONCAT_WS receives arguments with all NULL values, it will return an empty string of type varchar (1). CONCAT_WS ignores null values during concatenation, and does not add the separator between null values. Therefore, CONCAT_WS can cleanly handle concatenation of strings that might have “blank” values – for example, a second address field.
What is the function concat WS in MySQL?
CONCAT_WS () stands for Concatenate With Separator and is a special form of CONCAT (). The first argument is the separator for the rest of the arguments. The separator is added between the strings to be concatenated. The separator can be a string, as can the rest of the arguments. If the separator is NULL, the result is NULL.
Is there a way to skip empty strings in concat?
CONCAT_WS () does not skip empty strings. However, it does skip any NULL values after the separator argument. CONCAT_WS still produces null for me if the first field is Null. I solved this by adding a zero length string at the beginning as in
How to exclude null values inside concat MySQL?
The first argument is the separator for the rest of the arguments. The separator is added between the strings to be concatenated. The separator can be a string, as can the rest of the arguments. If the separator is NULL, the result is NULL. CONCAT_WS () does not skip empty strings. However, it does skip any NULL values after the separator argument.