[nongnu] elpa/emacsql 54c180017e 138/427: Add :pragma and note in README.

[ELPA Syncer]

branch: elpa/emacsql
commit 54c180017e21a8e441480c915c8b44fd997b254a
Author: Christopher Wellons <wellons@nullprogram.com>
Commit: Christopher Wellons <wellons@nullprogram.com>

    Add :pragma and note in README.
---
 README.md  | 17 +++++++++++++++--
 emacsql.el |  4 ++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index e58c86ce2b..8c554d7a9b 100644
--- a/README.md
+++ b/README.md
@@ -93,8 +93,13 @@ the details on what each of these means.
  :foreign (subjectid subject id :on-delete :cascade))
 ```
 
-Put the keys in a vector if the reference is composite, but remember
-that the cardinality must match.
+Put the keys in a vector if the reference is composite. Also remember
+that foreign key checks are currently disabled by default in SQLite,
+so you'll need to enable it for each connection.
+
+```el
+(emacsql db [:pragma (= foreign_keys on)])
+```
 
 ## Operators
 
@@ -271,6 +276,14 @@ Provides `UNION`, `UNION ALL`, `DIFFERENCE`, and `EXCEPT`.
 [:select * :from sales :union :select * :from accounting]
 ```
 
+#### :pragma `<expr>`
+
+Provides `PRAGMA`.
+
+```el
+(emacsql db [:pragma (= foreign_keys on)])
+```
+
 ### Templates
 
 To make statement compilation faster, and to avoid making you build up
diff --git a/emacsql.el b/emacsql.el
index 6e44c2a2bd..158a23e439 100644
--- a/emacsql.el
+++ b/emacsql.el
@@ -678,6 +678,10 @@ definitions for return from a `emacsql-defexpander'."
 (emacsql-defexpander :except ()
   (list "EXCEPT"))
 
+(emacsql-defexpander :pragma (expr)
+  (emacsql-with-vars "PRAGMA "
+    (expr expr)))
+
 (provide 'emacsql)
 
 ;;; emacsql.el ends here