- StarRocks
- Introduction to StarRocks
- Quick Start
- Deployment
- Deployment overview
- Prepare
- Deploy
- Deploy shared-nothing StarRocks
- Deploy and use shared-data StarRocks
- Manage
- Table Design
- Understand StarRocks table design
- Table types
- Data distribution
- Data compression
- Sort keys and prefix indexes
- Data Loading
- Concepts
- Overview of data loading
- Load data from a local file system or a streaming data source using HTTP PUT
- Load data from HDFS
- Load data from cloud storage
- Load data from Apache Kafka®
- Continuously load data from Apache Kafka®
- Load data from Apache Sparkâ„¢
- Load data using INSERT
- Load data using Stream Load transaction interface
- Realtime synchronization from MySQL
- Continuously load data from Apache Flink®
- Change data through loading
- Transform data at loading
- Data Unloading
- Query Data Lakes
- Query Acceleration
- Gather CBO statistics
- Synchronous materialized views
- Asynchronous materialized views
- Colocate Join
- Lateral Join
- Query Cache
- Index
- Computing the Number of Distinct Values
- Sorted streaming aggregate
- Integrations
- Administration
- Management
- Data recovery
- User Privilege and Authentication
- Performance Tuning
- Reference
- SQL Reference
- User Account Management
- Cluster Management
- ADD SQLBLACKLIST
- ADMIN CANCEL REPAIR TABLE
- ADMIN CHECK TABLET
- ADMIN REPAIR TABLE
- ADMIN SET CONFIG
- ADMIN SET REPLICA STATUS
- ADMIN SHOW CONFIG
- ADMIN SHOW REPLICA DISTRIBUTION
- ADMIN SHOW REPLICA STATUS
- ALTER RESOURCE GROUP
- ALTER STORAGE VOLUME
- ALTER SYSTEM
- CANCEL DECOMMISSION
- CREATE FILE
- CREATE RESOURCE GROUP
- CREATE STORAGE VOLUME
- DELETE SQLBLACKLIST
- DESC STORAGE VOLUME
- DROP FILE
- DROP RESOURCE GROUP
- DROP STORAGE VOLUME
- EXPLAIN
- INSTALL PLUGIN
- KILL
- SET
- SET DEFAULT STORAGE VOLUME
- SHOW BACKENDS
- SHOW BROKER
- SHOW COMPUTE NODES
- SHOW FILE
- SHOW FRONTENDS
- SHOW FULL COLUMNS
- SHOW INDEX
- SHOW PLUGINS
- SHOW PROC
- SHOW PROCESSLIST
- SHOW RESOURCE GROUP
- SHOW SQLBLACKLIST
- SHOW STORAGE VOLUMES
- SHOW TABLE STATUS
- SHOW VARIABLES
- UNINSTALL PLUGIN
- DDL
- ALTER DATABASE
- ALTER MATERIALIZED VIEW
- ALTER TABLE
- ALTER VIEW
- ALTER RESOURCE
- ANALYZE TABLE
- BACKUP
- CANCEL ALTER TABLE
- CANCEL BACKUP
- CANCEL RESTORE
- CREATE ANALYZE
- CREATE DATABASE
- CREATE EXTERNAL CATALOG
- CREATE FUNCTION
- CREATE INDEX
- CREATE MATERIALIZED VIEW
- CREATE REPOSITORY
- CREATE RESOURCE
- CREATE TABLE
- CREATE TABLE AS SELECT
- CREATE TABLE LIKE
- CREATE VIEW
- DROP ANALYZE
- DROP CATALOG
- DROP DATABASE
- DROP FUNCTION
- DROP INDEX
- DROP MATERIALIZED VIEW
- DROP REPOSITORY
- DROP RESOURCE
- DROP STATS
- DROP TABLE
- DROP VIEW
- HLL
- KILL ANALYZE
- RECOVER
- REFRESH EXTERNAL TABLE
- RESTORE
- SET CATALOG
- SHOW ANALYZE JOB
- SHOW ANALYZE STATUS
- SHOW FUNCTION
- SHOW META
- SHOW RESOURCES
- TRUNCATE TABLE
- USE
- DML
- ALTER LOAD
- ALTER ROUTINE LOAD
- BROKER LOAD
- CANCEL LOAD
- CANCEL EXPORT
- CANCEL REFRESH MATERIALIZED VIEW
- CREATE ROUTINE LOAD
- DELETE
- DROP TASK
- EXPORT
- GROUP BY
- INSERT
- PAUSE ROUTINE LOAD
- REFRESH MATERIALIZED VIEW
- RESUME ROUTINE LOAD
- SELECT
- SHOW ALTER TABLE
- SHOW ALTER MATERIALIZED VIEW
- SHOW BACKUP
- SHOW CATALOGS
- SHOW CREATE CATALOG
- SHOW CREATE DATABASE
- SHOW CREATE MATERIALIZED VIEW
- SHOW CREATE TABLE
- SHOW CREATE VIEW
- SHOW DATA
- SHOW DATABASES
- SHOW DELETE
- SHOW DYNAMIC PARTITION TABLES
- SHOW EXPORT
- SHOW LOAD
- SHOW MATERIALIZED VIEWS
- SHOW PARTITIONS
- SHOW PROPERTY
- SHOW REPOSITORIES
- SHOW RESTORE
- SHOW ROUTINE LOAD
- SHOW ROUTINE LOAD TASK
- SHOW SNAPSHOT
- SHOW TABLES
- SHOW TABLET
- SHOW TRANSACTION
- SPARK LOAD
- STOP ROUTINE LOAD
- STREAM LOAD
- SUBMIT TASK
- UPDATE
- Auxiliary Commands
- Data Types
- Keywords
- Function Reference
- Function list
- Java UDFs
- Window functions
- Lambda expression
- Aggregate Functions
- any_value
- approx_count_distinct
- array_agg
- avg
- bitmap
- bitmap_agg
- count
- corr
- covar_pop
- covar_samp
- group_concat
- grouping
- grouping_id
- hll_empty
- hll_hash
- hll_raw_agg
- hll_union
- hll_union_agg
- max
- max_by
- min
- min_by
- multi_distinct_sum
- multi_distinct_count
- percentile_approx
- percentile_cont
- percentile_disc
- retention
- stddev
- stddev_samp
- sum
- variance, variance_pop, var_pop
- var_samp
- window_funnel
- Array Functions
- all_match
- any_match
- array_agg
- array_append
- array_avg
- array_concat
- array_contains
- array_contains_all
- array_cum_sum
- array_difference
- array_distinct
- array_filter
- array_generate
- array_intersect
- array_join
- array_length
- array_map
- array_max
- array_min
- array_position
- array_remove
- array_slice
- array_sort
- array_sortby
- array_sum
- arrays_overlap
- array_to_bitmap
- cardinality
- element_at
- reverse
- unnest
- Bit Functions
- Bitmap Functions
- base64_to_bitmap
- bitmap_agg
- bitmap_and
- bitmap_andnot
- bitmap_contains
- bitmap_count
- bitmap_from_string
- bitmap_empty
- bitmap_has_any
- bitmap_hash
- bitmap_intersect
- bitmap_max
- bitmap_min
- bitmap_or
- bitmap_remove
- bitmap_subset_in_range
- bitmap_subset_limit
- bitmap_to_array
- bitmap_to_base64
- bitmap_to_string
- bitmap_union
- bitmap_union_count
- bitmap_union_int
- bitmap_xor
- intersect_count
- sub_bitmap
- to_bitmap
- JSON Functions
- Overview of JSON functions and operators
- JSON operators
- JSON constructor functions
- JSON query and processing functions
- Map Functions
- Binary Functions
- Conditional Functions
- Cryptographic Functions
- Date Functions
- add_months
- adddate
- convert_tz
- current_date
- current_time
- current_timestamp
- date
- date_add
- date_diff
- date_format
- date_slice
- date_sub, subdate
- date_trunc
- datediff
- day
- dayname
- dayofmonth
- dayofweek
- dayofyear
- days_add
- days_diff
- days_sub
- from_days
- from_unixtime
- hour
- hours_add
- hours_diff
- hours_sub
- last_day
- makedate
- microseconds_add
- microseconds_sub
- minute
- minutes_add
- minutes_diff
- minutes_sub
- month
- monthname
- months_add
- months_diff
- months_sub
- next_day
- now
- previous_day
- quarter
- second
- seconds_add
- seconds_diff
- seconds_sub
- str_to_date
- str2date
- time_slice
- time_to_sec
- timediff
- timestamp
- timestampadd
- timestampdiff
- to_date
- to_days
- unix_timestamp
- utc_timestamp
- week
- week_iso
- weekofyear
- weeks_add
- day_of_week_iso
- weeks_diff
- weeks_sub
- year
- years_add
- years_diff
- years_sub
- Geographic Functions
- Math Functions
- String Functions
- append_trailing_char_if_absent
- ascii
- char
- char_length
- character_length
- concat
- concat_ws
- ends_with
- find_in_set
- group_concat
- hex
- hex_decode_binary
- hex_decode_string
- instr
- lcase
- left
- length
- locate
- lower
- lpad
- ltrim
- money_format
- null_or_empty
- parse_url
- repeat
- replace
- reverse
- right
- rpad
- rtrim
- space
- split
- split_part
- starts_with
- strleft
- strright
- str_to_map
- substring
- trim
- ucase
- unhex
- upper
- url_decode
- url_encode
- Pattern Matching Functions
- Percentile Functions
- Scalar Functions
- Struct Functions
- Table Functions
- Utility Functions
- cast function
- hash function
- AUTO_INCREMENT
- Generated columns
- System variables
- User-defined variables
- Error code
- System limits
- AWS IAM policies
- SQL Reference
- FAQ
- Benchmark
- Ecosystem Release Notes
- Developers
- Contribute to StarRocks
- Code Style Guides
- Use the debuginfo file for debugging
- Development Environment
- Trace Tools
Edit
group_concat
Description
group_concat concatenates non-null values into one string from a group, with a separator argument, which is ',' by default if not specified.
Syntax
VARCHAR GROUP_CONCAT([DISTINCT] expr [,expr ...]
[ORDER BY {unsigned_integer | col_name | expr}
[ASC | DESC] [,col_name ...]]
[SEPARATOR str_val])
Parameters
expr
: the values to concatenate, ignoring null. It should be cast to VARCHAR. They can be optionally specifiedDISTINCT
to eliminate duplicate values. Moreexpr
are concatenated directly, useconcat()
orconcat_ws
to specify formats.- order-by items can be unsigned integers (identify
expr
, starting from 1), column names or normal expressions. To sort in reverse order, add the DESC (descending) keyword to the name of the column you are sorting by in the ORDER BY clause. The default is ascending order; this may be specified explicitly using the ASC keyword str_val
: the optional separator is used to concat non-null values from different rows. If it is not specified,,
(a comma) is used by default.
Return value
Returns a string value for each group, but returns NULL if there are no non-NULL values.
set group_concat_max_len
to limit the length of output string from a group, its default value is 1024, minimal value is 4.
Examples
CREATE TABLE `ss` (
`id` int(11) NULL COMMENT "",
`name` varchar(255) NULL COMMENT "",
`subject` varchar(255) NULL COMMENT "",
`score` int(11) NULL COMMENT ""
) ENGINE=OLAP
DUPLICATE KEY(`id`)
DISTRIBUTED BY HASH(`id`) BUCKETS 4
PROPERTIES (
"replication_num" = "1"
);
insert into ss values (1,"Tom","English",90);
insert into ss values (1,"Tom","Math",80);
insert into ss values (2,"Tom","English",NULL);
insert into ss values (2,"Tom",NULL,NULL);
insert into ss values (3,"May",NULL,NULL);
insert into ss values (3,"Ti","English",98);
insert into ss values (4,NULL,NULL,NULL);
insert into ss values (NULL,"Ti","Phy",98);
select id, group_concat(distinct name,subject order by score) as res from ss group by id order by id;
+------+--------------------+
| id | res |
+------+--------------------+
| NULL | TiPhy |
| 1 | TomMath,TomEnglish |
| 2 | NULL |
| 3 | TiEnglish |
| 4 | NULL |
+------+--------------------+
mysql> select id, group_concat(distinct concat(name,'-',subject) order by score) as res from ss group by id order by id;
+------+----------------------+
| id | res |
+------+----------------------+
| NULL | Ti-Phy |
| 1 | Tom-Math,Tom-English |
| 2 | NULL |
| 3 | Ti-English |
| 4 | NULL |
+------+----------------------+
select group_concat(name) as res from ss;
+---------------------------+
| res |
+---------------------------+
| Tom,Tom,Ti,Tom,Tom,May,Ti |
+---------------------------+
select group_concat(distinct name) as res from ss where id < 0;
+------+
| res |
+------+
| NULL |
+------+
set group_concat_max_len = 6;
select id, group_concat(distinct name,subject order by score) as res from ss group by id order by id;
+------+--------+
| id | res |
+------+--------+
| NULL | TiPhy |
| 1 | TomMat |
| 2 | NULL |
| 3 | TiEngl |
| 4 | NULL |
+------+--------+
keyword
GROUP_CONCAT,CONCAT,ARRAY_AGG
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