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Overview

The stock operations module tracks all inventory movements in your store, providing a complete audit trail of stock level changes. Every movement records what product was affected, the quantity, the type of operation, and which employee authorized it.
Stock operations are also called “movimientos de inventario” or “movimientos de stock” in the system.

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Types of Stock Movements

The system supports three types of inventory operations:

Entrada

Stock EntryIncreases inventory when:
  • New merchandise arrives
  • Returns from customers
  • Transfers from other locations

Salida

Stock ExitDecreases inventory when:
  • Products are sold
  • Items are transferred out
  • Returns to suppliers

Ajuste

Stock AdjustmentCorrects inventory for:
  • Physical count discrepancies
  • Damaged goods removal
  • Lost or found items

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Accessing Stock Operations

Navigate to the Movimientos de Inventario page (movimientos.php) from the main navigation menu.

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Interface Layout

The page consists of:
  1. Quick-add form (top): Horizontal form for registering new movements
  2. Movement history table (below): Chronological list of all movements (newest first)

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Registering a Stock Movement

1

Select the product

In the “Prenda” dropdown, select the product for which you’re recording a movement.The dropdown shows:
  • All products currently in the system
  • Product names only (not IDs)
  • Loaded from the prenda table
If the product you need isn’t listed, you must create it first in the Product Management section.
2

Select the movement type

In the “Tipo” dropdown, choose the operation type:entrada (Entry)
  • Use when stock is increasing
  • Adds quantity to stock_actual
  • Displayed in green in the history table
salida (Exit)
  • Use when stock is decreasing
  • Subtracts quantity from stock_actual
  • Displayed in red in the history table
ajuste (Adjustment)
  • Use for corrections or inventory reconciliation
  • Can increase or decrease stock (based on quantity sign)
  • Displayed in red in the history table
3

Enter the quantity

In the “Cantidad” field, enter the number of units:For entries and exits:
  • Enter positive numbers only
  • The system automatically adds or subtracts based on movement type
  • Example: 10 for 10 units
For adjustments:
  • Enter positive or negative numbers
  • Positive increases stock: +5 or 5
  • Negative decreases stock: -3
Be careful with quantities—incorrect entries directly affect your inventory levels. There is no undo function.
4

Select the authorizing employee

In the “Empleado que autoriza” dropdown, select the employee responsible for this movement.
This creates an audit trail. Always select the actual person performing the operation, not a default user.
5

Submit the movement

Click the “Registrar” button (green, full-width) to record the movement.
6

Verify the operation

After successful registration:
  • Page reloads automatically
  • New movement appears at the top of the history table
  • Product’s stock_actual has been updated
  • Form clears, ready for the next entry
Go to the main inventory page to verify the product’s stock level was updated correctly.

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How Stock Updates Work

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Automatic Stock Calculation

When you register a movement, the system automatically updates the product’s current stock: 
// Determine the operator based on movement type
$operador = ($_POST['tipo'] == 'entrada') ? "+" : "-";
if($_POST['tipo'] == 'ajuste') $operador = "+"; // Adjustments handle their own sign

// Update the product's stock_actual
$conn->query("UPDATE prenda 
              SET stock_actual = stock_actual $operador {$_POST['cant']} 
              WHERE id_prenda = {$_POST['prenda']}");

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Movement Type Logic

Movement TypeOperatorEffect on Stock
entrada+Increases stock_actual by quantity
salida-Decreases stock_actual by quantity
ajuste+Adds quantity (can be negative) to stock_actual

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Examples

Example 1: Stock Entry
  • Product: Camisa Oxford (current stock: 10)
  • Type: entrada
  • Quantity: 20
  • Result: 10 + 20 = 30 (new stock)
Example 2: Stock Exit
  • Product: Pantalón Mezclilla (current stock: 50)
  • Type: salida
  • Quantity: 5
  • Result: 50 - 5 = 45 (new stock)
Example 3: Positive Adjustment
  • Product: Vestido Floral (current stock: 15)
  • Type: ajuste
  • Quantity: 3
  • Result: 15 + 3 = 18 (corrected stock after physical count found 3 extra units)
Example 4: Negative Adjustment
  • Product: Bufanda Lana (current stock: 25)
  • Type: ajuste
  • Quantity: -2
  • Result: 25 + (-2) = 23 (corrected stock after 2 damaged units removed)

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Viewing Movement History

The movement history table displays all operations in reverse chronological order (newest first).

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Table Columns

ColumnDescription
FechaDate and time of the movement (YYYY-MM-DD HH:MM:SS)
PrendaProduct name
TipoMovement type (ENTRADA, SALIDA, or AJUSTE) in uppercase, color-coded
Cant.Quantity (number of units)
EmpleadoEmployee who authorized the movement

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Color Coding

Movement types are color-coded for quick visual identification:
  • ENTRADA: Green text (text-success class)
  • SALIDA: Red text (text-danger class)
  • AJUSTE: Red text (text-danger class)
The color coding helps you quickly scan for unusual patterns, such as many exits in a row or frequent adjustments.

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Query Behind the Table

SELECT m.*, p.nombre as p_nom, e.nombre as e_nom 
FROM movimiento_stock m 
JOIN prenda p ON m.id_prenda = p.id_prenda 
JOIN empleado e ON m.id_empleado = e.id_empleado 
ORDER BY fecha DESC

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Movement Validation and Constraints

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Current Limitations

The system currently does not validate that stock doesn’t go negative. You can record exits or adjustments that result in negative inventory levels.
Example of what’s allowed but shouldn’t be:
  • Current stock: 5 units
  • Record salida: 10 units
  • Result: -5 units (negative stock!)
This is a known limitation that requires careful manual monitoring.

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Best Practices to Avoid Negative Stock

1

Check current stock before recording exits

Before registering a salida, view the product in the inventory page to verify sufficient stock exists.
2

Use adjustments for corrections

If you discover a stock count error, use ajuste (not salida) and enter the exact difference, not the absolute quantity.
3

Implement physical stock checks

Regularly perform physical counts and reconcile with system stock using adjustments.
4

Train staff on movement types

Ensure everyone understands when to use entrada vs. salida vs. ajuste.

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Future Enhancement Recommendations

The system could be improved with: 
// Validation before stock update
$stmt = $conn->prepare("SELECT stock_actual FROM prenda WHERE id_prenda = ?");
$stmt->execute([$_POST['prenda']]);
$current_stock = $stmt->fetchColumn();

if ($tipo == 'salida' && $cantidad > $current_stock) {
    die("Error: Stock insuficiente. Stock actual: $current_stock, cantidad solicitada: $cantidad");
}

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Common Use Cases

When you receive a shipment:
  1. First, register the reception (if not already done):
    • Go to Recepciones de Mercancía (registros.php)
    • Record which product, employee, and supplier
  2. Then, record the stock entry:
    • Go to Movimientos de Inventario (movimientos.php)
    • Select the product
    • Choose entrada as type
    • Enter the quantity received
    • Select the receiving employee
    • Click Registrar
The reception record (registros) documents WHERE the stock came from. The stock movement (movimientos) updates the actual inventory count.
When products are sold (without an integrated POS system):
  1. Navigate to Movimientos de Inventario
  2. Select the product sold
  3. Choose salida as type
  4. Enter the quantity sold
  5. Select the employee who processed the sale
  6. Click Registrar
This manual process is prone to errors. Consider integrating with a POS system or implementing a dedicated sales module.
During periodic inventory audits:
  1. Perform physical count: Count actual units for each product
  2. Compare with system stock: Check current stock_actual in the inventory page
  3. Record adjustments for discrepancies:
    • Go to Movimientos de Inventario
    • Select the product
    • Choose ajuste as type
    • Calculate the difference:
      • If physical > system: Enter positive number (e.g., +5)
      • If physical < system: Enter negative number (e.g., -3)
    • Select the auditing employee
    • Click Registrar
Example:
  • System shows: 50 units
  • Physical count: 47 units
  • Difference: -3
  • Record adjustment: ajuste with quantity -3
When products must be removed from inventory due to damage:
  1. Navigate to Movimientos de Inventario
  2. Select the damaged product
  3. Choose ajuste as type (not salida)
  4. Enter negative quantity (e.g., -2 for 2 damaged units)
  5. Select the employee who identified/removed the items
  6. Click Registrar
Use ajuste instead of salida for damaged goods to distinguish between actual sales and inventory shrinkage in reporting.
While not explicitly supported, you can simulate inter-location transfers:At source location:
  1. Record a salida for the transferred quantity
  2. Note in a separate log: “Transfer to [Location Name]”
At destination location:
  1. Record an entrada for the received quantity
  2. Note in a separate log: “Transfer from [Location Name]”
This manual process doesn’t link the two movements. Consider developing a dedicated transfer module for multi-location operations.

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Troubleshooting

Possible causes:
  1. Wrong movement type selected:
    • You selected entrada but meant salida (or vice versa)
    • Solution: Record a correcting ajuste with opposite quantity
  2. Incorrect quantity entered:
    • You entered 100 instead of 10
    • Solution: Calculate the difference and record an ajuste
  3. Multiple movements not visible:
    • Several users recorded movements simultaneously
    • Solution: Review the full movement history table
  4. Direct database edit:
    • Someone modified stock_actual directly in the database
    • Solution: Perform physical count and use ajuste to correct
If a product shows negative stock:Identify the cause:
  1. Check the movement history for that product
  2. Look for large salida entries that exceeded available stock
  3. Identify when the stock went negative
Correct the issue:
  1. Perform a physical count to determine actual stock
  2. Record an ajuste to set stock to the correct value:
    • Current stock: -5
    • Actual count: 0
    • Adjustment: +5
Negative stock indicates a process failure. Investigate why the salida was recorded without checking available inventory.
If the product you need isn’t in the Prenda dropdown:
  1. Verify the product exists: Go to the inventory page and search for it
  2. Create the product if missing: Use Nueva Prenda to add it
  3. Refresh the movements page: After creating the product, refresh movimientos.php
  4. Check database: Query the prenda table to confirm the product exists
The dropdown is populated on page load. If you create a product in another tab, refresh movimientos.php to see it.
If an employee isn’t available in the “Empleado que autoriza” dropdown:
  1. Verify employee exists: Go to Gestión de Empleados
  2. Create employee if missing: Use the registration form
  3. Refresh the movements page: After creating, refresh movimientos.php
  4. Check for JavaScript errors: Open browser console (F12)
If a movement seems to register but doesn’t show in the table:
  1. Check for error messages: Look at the top of the page
  2. Verify database insertion: Check if the record exists in movimiento_stock table
  3. Check date/time: Ensure your server’s clock is correct (movements sort by fecha)
  4. Refresh the page: Try a hard refresh (Ctrl+F5 or Cmd+Shift+R)
  5. Review query: The table uses a JOIN query that might fail if related records are missing
There is no built-in undo function. To reverse a movement:Manual reversal:
  1. Identify the incorrect movement in the history table
  2. Note its type, product, and quantity
  3. Record a new movement with the opposite effect:
    • If original was entrada of 10: Record salida of 10
    • If original was salida of 5: Record entrada of 5
    • If original was ajuste of +3: Record ajuste of -3
The reversal creates a new record—it doesn’t delete the original. This maintains audit trail integrity.

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Integration with Other Modules

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Product Management Integration

Stock movements directly update the stock_actual field in the prenda table: 
UPDATE prenda 
SET stock_actual = stock_actual + 20 
WHERE id_prenda = 5;
When you view the inventory page (index.php), the stock column displays this updated value.

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Merchandise Reception Integration

While movements and receptions are related, they’re recorded separately:
  • Recepciones de Mercancía (registros.php): Tracks WHAT was received, from WHICH supplier, by WHICH employee
  • Movimientos de Inventario (movimientos.php): Updates the actual stock count
Workflow recommendation: When receiving goods, record both:
  1. First, the reception (registros) for audit trail
  2. Then, the stock entry (movimientos) to update inventory

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Employee Audit Integration

Every movement links to an employee via id_empleado: 
SELECT e.nombre, COUNT(*) as movement_count
FROM movimiento_stock m
JOIN empleado e ON m.id_empleado = e.id_empleado
GROUP BY e.nombre
ORDER BY movement_count DESC;
This query shows which employees process the most stock movements.

Managing Products

Learn how to create products and view current stock levels

Managing Employees

Set up employee accounts for movement authorization tracking

Database Schema

Understand the movimiento_stock table structure

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Best Practices

1

Always verify stock before exits

Check the current stock level in the inventory page before recording salida movements to avoid negative stock.
2

Use descriptive employee names

Always select the actual employee performing the operation—accurate audit trails depend on this.
3

Use the correct movement type

  • entrada: When stock physically arrives
  • salida: When stock physically leaves (sales, transfers out)
  • ajuste: For corrections, damaged goods, or reconciliation
4

Document adjustments externally

When recording adjustments, maintain a separate log explaining WHY the adjustment was needed (e.g., “Physical count found 3 extra units” or “Removed 2 damaged shirts”).
5

Regular physical counts

Schedule periodic inventory audits:
  • Weekly for high-turnover items
  • Monthly for standard items
  • Quarterly for slow-moving items
Reconcile discrepancies immediately using ajuste movements.
6

Review movement history regularly

Periodically review the movement history table for:
  • Unusual patterns (many adjustments for one product)
  • Frequent negative corrections (indicates process issues)
  • High volume of movements by one employee (potential audit flag)
7

Implement double-entry verification

For high-value or critical inventory:
  • Have one employee perform the operation
  • Have a second employee verify and authorize
  • Document both employees in a separate log

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Reporting and Analytics (Future Enhancement)

While not currently built into the system, you could generate useful reports with SQL queries:

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Movement Volume by Type

SELECT tipo_movimiento, COUNT(*) as cantidad_movimientos
FROM movimiento_stock
GROUP BY tipo_movimiento;

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Most Active Products

SELECT p.nombre, COUNT(*) as total_movimientos
FROM movimiento_stock m
JOIN prenda p ON m.id_prenda = p.id_prenda
GROUP BY p.nombre
ORDER BY total_movimientos DESC
LIMIT 10;

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Employee Movement Activity

SELECT e.nombre, tipo_movimiento, COUNT(*) as cantidad
FROM movimiento_stock m
JOIN empleado e ON m.id_empleado = e.id_empleado
GROUP BY e.nombre, tipo_movimiento
ORDER BY e.nombre, tipo_movimiento;

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Daily Movement Summary

SELECT DATE(fecha) as dia, tipo_movimiento, SUM(cantidad) as total_unidades
FROM movimiento_stock
GROUP BY DATE(fecha), tipo_movimiento
ORDER BY dia DESC;
Consider working with your developer to add a reporting dashboard that visualizes these queries.

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