update

daten-abfragen/notes.md

@@ -53,4 +53,8 @@
 - `SELECT CONCAT(spalte1, spalte2, ...)`  
   Verknüpft mehrere Spalten oder Zeichenketten miteinander und gibt die kombinierte Zeichenkette zurück.
 - `REPLACE(spalte, 'suchen', 'ersetzen')`  
-  Ersetzt alle Vorkommen des Suchstrings durch den Ersetzungsstring in der angegebenen Spalte.
+  Ersetzt alle Vorkommen des Suchstrings durch den Ersetzungsstring in der angegebenen Spalte.
+
+## Sonderfall `NULL`
+Mit `IS NULL` oder `IS NOT NULL` kann geprüft werden, ob ein Wert in einer Spalte `NULL` ist oder nicht.
+Mit `NULL` kann nicht verglichen werden. `NULL = NULL` ergibt `NULL`, nicht `TRUE` oder `FALSE`.

daten-manipulieren/datatypes.md

@@ -0,0 +1,70 @@
+# MySQL Data Types Cheatsheet
+
+## 1. **Numeric Data Types**
+
+### Integer Types
+| Data Type | Storage | Range (Signed) | Range (Unsigned) |
+|-----------|---------|---------------|-------------------|
+| `TINYINT` | 1 byte | -128 to 127 | 0 to 255 |
+| `SMALLINT` | 2 bytes | -32,768 to 32,767 | 0 to 65,535 |
+| `MEDIUMINT` | 3 bytes | -8,388,608 to 8,388,607 | 0 to 16,777,215 |
+| `INT` / `INTEGER` | 4 bytes | -2,147,483,648 to 2,147,483,647 | 0 to 4,294,967,295 |
+| `BIGINT` | 8 bytes | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 | 0 to 18,446,744,073,709,551,615 |
+
+### Floating-Point Types
+| Data Type | Storage | Range | Precision |
+|-----------|---------|--------|-----------|
+| `FLOAT(m,d)` | 4 bytes | Approx. ±3.4E38 | Rounded due to floating-point approximation |
+| `DOUBLE(m,d)` / `REAL` | 8 bytes | Approx. ±1.8E308 | Higher precision than FLOAT but still subject to rounding |
+| `DECIMAL(m,d)` / `NUMERIC(m,d)` | Varies | Exact fixed-point values | Precise representation, no rounding errors |
+
+#### **Floating-Point Precision Considerations**
+- **`FLOAT` and `DOUBLE`** are subject to rounding errors due to floating-point representation and should not be used where exact precision is required (e.g., financial applications).
+- **`DECIMAL`** is a fixed-point type that maintains exact precision and is ideal for storing monetary values, making it the preferred choice for banking applications.
+
+## 2. **String Data Types**
+| Data Type | Storage | Description |
+|-----------|---------|-------------|
+| `CHAR(n)` | 1 byte per character | Fixed-length string (0-255 characters) |
+| `VARCHAR(n)` | 1 byte per character + 1 or 2 bytes | Variable-length string (0-65,535 characters) |
+| `TEXT` | Varies | Large text field (0-4GB depending on type) |
+| `TINYTEXT` | Up to 255 bytes | Small text field |
+| `TEXT` | Up to 65,535 bytes | Standard text field |
+| `MEDIUMTEXT` | Up to 16,777,215 bytes | Medium text field |
+| `LONGTEXT` | Up to 4GB | Very large text field |
+| `BLOB` | Varies | Binary large object (same size variations as TEXT) |
+
+## 3. **Date and Time Data Types**
+| Data Type | Storage | Format | Range |
+|-----------|---------|--------|--------|
+| `DATE` | 3 bytes | YYYY-MM-DD | 1000-01-01 to 9999-12-31 |
+| `DATETIME` | 8 bytes | YYYY-MM-DD HH:MM:SS | 1000-01-01 00:00:00 to 9999-12-31 23:59:59 |
+| `TIMESTAMP` | 4 bytes | YYYY-MM-DD HH:MM:SS | 1970-01-01 00:00:01 UTC to 2038-01-19 03:14:07 UTC |
+| `TIME` | 3 bytes | HH:MM:SS | -838:59:59 to 838:59:59 |
+| `YEAR` | 1 byte | YYYY | 1901 to 2155 |
+
+## 4. **Boolean Type**
+| Data Type | Alias For | Description |
+|-----------|-----------|-------------|
+| `BOOLEAN` | `TINYINT(1)` | Stores 0 (false) or 1 (true) |
+
+## 5. **Spatial Data Types**
+| Data Type | Description |
+|-----------|-------------|
+| `GEOMETRY` | Stores any spatial value |
+| `POINT` | Stores (X,Y) coordinate |
+| `LINESTRING` | Stores a line of multiple points |
+| `POLYGON` | Stores a polygon |
+
+## 6. **JSON Data Type**
+| Data Type | Description |
+|-----------|-------------|
+| `JSON` | Stores JSON-formatted data efficiently |
+
+### **Notes:**
+- Use `UNSIGNED` for numeric types when negative values are not needed.
+- `DECIMAL(m,d)` is preferred for exact decimal values (e.g., financial applications).
+- Use `TEXT` for large text fields instead of `VARCHAR` when indexing is not required.
+- `TIMESTAMP` is useful for automatic time zone conversion, while `DATETIME` is better for absolute timestamps.
+- `JSON` is useful for semi-structured data storage.
+

daten-manipulieren/table-manipulation.sql

@@ -1,6 +1,47 @@
 create table if not exists stores
 (
-    street      varchar(100),
+    street      varchar(100) NOT NULL,
     description text
-)
+);
 
+alter table stores
+    add column name varchar(100);
+
+alter table stores
+    drop column name;
+
+alter table stores
+    add column name varchar(100) first; # Bei MySQL gibt es kein BEFORE, es gibt nur AFTER und FIRST
+
+alter table stores
+    modify column name varchar(100);
+
+alter table stores
+    add column city varchar(100) after street;
+
+alter table stores
+    add column rent decimal(8, 2);
+
+alter table stores
+    add column num_sales int unsigned; # Unsigned (nur positive Zahlen)
+
+INSERT INTO stores (street, city, description, rent, num_sales)
+VALUES ('123 Main St', 'New York', 'Spacious 2-bedroom apartment in the heart of downtown.', 2500.00, 5),
+       ('456 Elm St', 'Los Angeles', 'Modern loft with great city views and natural light.', 3200.50, 3),
+       ('789 Pine Ave', 'Chicago', 'Cozy studio close to public transport and shopping.', 1800.75, 7),
+       ('101 Maple Rd', 'San Francisco', 'Luxury penthouse with rooftop access and premium amenities.', 5500.00, 2),
+       ('202 Oak St', 'Miami', 'Beachfront condo with private balcony and ocean views.', 4200.25, 4);
+
+create table if not exists users
+(
+    id         int primary key auto_increment,
+    email      varchar(100) not null,
+    password   varchar(100) not null,
+    created_at timestamp default current_timestamp
+);
+
+insert into users (email, password)
+values ('test@test.de', '123456');
+
+alter table users
+    add column num_books int not null default 0;