# 6.4 Data Definition Language (DDL)

Part of: [6 Language](6-language.md)

Data Definition Language (DDL) is, generally speaking, the syntax for defining and modifying structures that store data. In HDFql, DDL consists of operations that enable the creation, alteration, renaming, copying, and deletion of HDF5 files, groups, datasets, attributes, and links. These operations begin with the keywords CREATE, ALTER, RENAME, COPY, or DROP.

## In this section

- [6.4.1 CREATE DIRECTORY](6-4-1-create-directory.md)
- [6.4.2 CREATE FILE](6-4-2-create-file.md)
- [6.4.3 CREATE GROUP](6-4-3-create-group.md)
- [6.4.4 CREATE DATASET](6-4-4-create-dataset.md)
- [6.4.5 CREATE ATTRIBUTE](6-4-5-create-attribute.md)
- [6.4.6 CREATE \[SOFT | HARD\] LINK](6-4-6-create-soft-hard-link.md)
- [6.4.7 CREATE EXTERNAL LINK](6-4-7-create-external-link.md)
- [6.4.8 ALTER DIMENSION](6-4-8-alter-dimension.md)
- [6.4.9 RENAME DIRECTORY](6-4-9-rename-directory.md)
- [6.4.10 RENAME FILE](6-4-10-rename-file.md)
- [6.4.11 RENAME](6-4-11-rename.md)
- [6.4.12 COPY FILE](6-4-12-copy-file.md)
- [6.4.13 COPY](6-4-13-copy.md)
- [6.4.14 DROP DIRECTORY](6-4-14-drop-directory.md)
- [6.4.15 DROP FILE](6-4-15-drop-file.md)
- [6.4.16 DROP](6-4-16-drop.md)